AU2013200333A1

AU2013200333A1 - Sp35 Antibodies and Uses Thereof

Info

Publication number: AU2013200333A1
Application number: AU2013200333A
Authority: AU
Inventors: Christilyn P. Graff; Sha Mi; R. Blake Pepinsky; Zhaohui Shao
Original assignee: Biogen MA Inc
Current assignee: Biogen MA Inc
Priority date: 2005-07-08
Filing date: 2013-01-23
Publication date: 2013-02-14

Abstract

Endogenous Sp35 is a negative regulator for neuronal survival, axon regeneration, oligodendrocyte differentiation and myelination (Negative Regulator). Molecules that block endogenous Sp35 function, such as anti-Sp35 antibodies can be used as therapeutics for the treatment of neuron and oligodendrocyte dysfunction. The present invention provides antibodies specific for Sp35, and methods of using such antibodies as antagonists of endogenous Sp35 function. The invention further provides specific hybridoma and phage library-derived monoclonal antibodies, nucleic acids encoding these antibodies, and vectors and host cells comprising these antibodies. The invention further provides methods of promoting oligodendrocyte survival and myelination in a vertebrate, comprising administering to a vertebrate in need of such treatment an effective amount of an anti-Sp35 antibody.

Description

SP35 ANTIBODIES AND USES THEREOF BACKGROUND OF THE INVENTION Field of the Invention [00011 This invention relates to neurology, neurobiology and molecular biology. More particularly, this invention relates to molecules and methods for treatment of neurological diseases, disorders and injuries such as spinal cord injury. Background of the Invention [00021 Axons and dendrites extend from neurons. The distal tip of an extending axon or neurite includes a specialized region, known as the growth cone. Growth cones sense the local environment and guide axonal growth toward a neuron's target cell. Growth cones respond to environmental cues, for example, surface adhesiveness, growth factors, neurotransmitters and electric fields. The growth cones generally advance at a rate of one to two millimeters per day. The growth cone explores the area ahead of it and on either side, by means of elongations classified as lamellipodia and filopodia. When an elongation contacts an unfavorable surface, it withdraws. When an elongation contacts a favorable growth surface, it continues to extend and guides the growth cone in that direction. When the growth cone reaches an appropriate target cell a synaptic connection is created. [00031 Nerve cell function is influenced by contact between neurons and other cells in their immediate environment (Rutishauser, et al., 1988, Physiol. Rev. 68:819). These cells include specialized glial cells, oligodendrocytes in the central nervous system (CNS), and Schwann cells in the peripheral nervous system (PNS), which sheathe the neuronal axon with myelin (Lenike, 1992, in An Introduction to Molecular Neurobiology, Z. Hall, Ed., p. 281, Sinauer). [00041 CNS neurons have the inherent potential to regenerate after injury, but they are inhibited from doing so by inhibitory proteins present in myelin (Brittis et al., 2001, Neuron 30:11-14; Jones et al., 2002, J. Neurosci. 22:2792-2803; Grimpe et al., 2002, J. Neurosci.:22:3144-3160). [00051 Several myelin inhibitory proteins found on oligodendrocytes have been characterized. Known examples of myelin inhibitory proteins include NogoA (Chen et al., Nature, 2000, 403, 434 439; Grandpre et al., Nature 2000, 403, 439-444), myelin associated glycoprotein (MAG) (McKerracher et al., 1994, Neuron 13:805-811; Mukhopadhyay et al., 1994, Neuron 13:757-767) and oligodendrocyte glycoprotein (OM-gp), Mikol et al., 1988, J. Cell. Biol. 106:1273-1279). Each of these proteins has been separately shown to be a ligand for the neuronal Nogo receptor-1 (NgR1 (Wang et al., Nature 2002, 417, 941-944; Grandpre et al., Nature 2000, 403, 439-444; Chen et al., Nature, 2000, 403, 434-439; Domeniconi et al., Neuron 2002, published online June 28, 2002).

-2 [00061 Nogo receptor-1 (NgR1) is a GPI-anchored membrane protein that contains 8 leucine rich repeats (Fournier et al., 2001, Nature 409:341-346). Upon interaction with inhibitory proteins (e.g., NogoA, MAG and OM-gp), the NgR1 complex transduces signals that lead to growth cone collapse and inhibition of neurite outgrowth. [0007] There is an unmet need for molecules and methods for inhibiting NgRl-mediated growth cone collapse and the resulting inhibition of neurite outgrowth. Additionally there is a need for molecules which increase neuronal survival and axon regeneration. Particularly for the treatment of disease, disorders or injuries which involve axonal injury, neuronal or oligodendrocyte cell death, dernyelination or dymyelination or generally relate to the nervous system. [00081 Such diseases, disorders or injuries include, but are not limited to, multiple sclerosis (MS), progressive multifocal leukoencephalopathy (PML), encephalomyelitis (EPL), central pontine myelolysis (CPM), adrenoleukodystrophy, Alexander's disease, Pelizaeus Merzbacher disease (PMZ), Globoid cell Leucodystrophy (Krabbe's disease) and Wallerian Degeneration, optic neuritis, transverse myelitis, amylotrophic lateral sclerosis (ALS), Huntington's disease, Alzheimer's disease, Parkinson's disease, spinal cord injury, traumatic brain injury, post radiation injury, neurologic complications of chemotherapy, stroke, acute ischemic optic neuropathy, vitamin E deficiency, isolated vitamin E deficiency syndrome, AR, Bassen-Kornzweig syndrome, Marchiafava-Bignami syndrome, metachromatic leukodystrophy, trigeminal neuralgia, and Bell's palsy. Among these diseases, MS is the most widespread, affecting approximately 2.5 million people worldwide. [00091 MS generally begins with a relapsing-remitting pattern of neurologic involvement, which then progresses to a chronic phase with increasing neurological damage. MS is associated with the destruction of myelin, oligodendrocytes and axons localized to chronic lesions. The demyelination observed in MS is not always permanent and remyelination has been documented in early stages of the disease. Remyelination of neurons requires oligodendrocytes. [0010] Various disease-modifying treatments are available for MS, including the use of corticosteroids and immunomodulators such as interferon beta and Tysabri@. In addition, because of the central role of oligodendrocytes and myelination in MS, there have been efforts to develop therapies to increase oligodendrocyte numbers or enhance myelination. See, e.g., Cohen et al., U.S. Pat. No. 5,574,009; Chang et al., N. Engl. J. Med. 346: 165-73 (2002). However, there remains an urgent need to devise additional therapies for MS and other demyelination and dismyelination disorders. BRIEF SUMMARY OF THE INVENTION [0011] The present invention is based on the discovery that Sp35 (Sp35 is also designated in the literature as LINGO-1 and LRRN6) is expressed in oligodendrocytes and neuronal cells and negatively regulates oligodendrocyte/neuronal differentiation, survival and axon myelination. Furthermore, -3 certain antagonists of Sp35 promote survival, proliferation and differentiation of oligodendrocytes and neuronal cells, as well as myelination of neurons. Based on these discoveries, the invention relates generally to antibodies, antigen binding fragment or derivatives thereof which can be used as an antagonist of Sp35. Additionally, the invention generally relates to methods for treating various disease, disorders or injuries associated with demyelination, dysmyelination, oligodendrocyte/neuronal cell death or axonal injury by the administration of an Sp35 antagonist antibody or antigen binding fragment. [0012] In certain embodiments, the invention includes an isolated antibody or antigen binding fragment thereof which specifically binds to the same Sp35 epitope as a reference monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3PlDlO.2C3, 3PlE11.3B7, 3P2C6.3G10.21H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (Li02), 35-E04 (Li03), 36-C09 (Li04), 30-Al1 (LiO5), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (Li08), 36-A12 (Li09), 28-D02 (LilO), 30-BOl (Lil 1), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13). [00131 Certain embodiments of the invention include an isolated polypeptide comprising an imnmunoglobulin heavy chain variable region (VH) wherein the CDR1, CDR2 and CDR3 regions are selected from the polypeptide sequences shown in Table 4 or at least 80%, 85%, 90 or 95% identical to the polypeptide sequences shown in Table 4. [0014] Certain embodiments of the invention include an isolated polypeptide comprising an immunoglobulin light chain variable region (VL) wherein the CDR1, CDR2 and CDR3 regions are selected from the polypeptide sequences shown in Table 5 or at least 80%, 85%, 90% or 95% identical to the polypeptide sequences shown in Table 5. [0015] Certain embodiments of the invention include an isolated polypeptide comprising an immunoglobulin heavy chain variable region (VH) selected from the group consisting of SEQ ID NOs: 158 to 172, 372, 376, 380 and 384, as shown in Table 6, or at least 80%, 85%, 90% or 95% identical to said SEQ ID NOs: 158 to 172, 372, 376, 380 and 384 as shown in Table 6. [0016] Certain embodiments of the invention include an isolated polypeptide comprising an immunoglobulin light chain variable region (VL) selected from the group consisting of SEQ ID NOs: 273 to 286, 373, 377, 381 and 385, as shown in Table 8, or at least 80%, 85%, 90% or 95% identical to said SEQ ID NOs: 273 to 286, 373, 377, 381 and 385, as shown in Table 8. [0017] In additional embodiments, the invention includes an isolated polynucleotide comprising a nucleic acid encoding an immunoglobulin heavy chain variable region (VH) wherein the CDRI, CDR2 and CDR3 regions are selected from the group selected from the polynucleotide sequences shown in Table 4 or at least 80%, 85%, 90 or 95% identical to the polynucleotide sequences shown in Table 4.

-4 [00181 In other embodiments, the invention includes an isolated polynucleotide comprising a nucleic acid encoding an immunoglobulin light chain variable region (VL) wherein the CDR1, CDR2 and CDR3 regions are selected from the the polynucleotide sequences shown in Table 5 or at least 80%, 85%, 90% or 95% identical to the polynucleotide sequences shown in Table 5. [0019] Other embodiments of the invention include, an isolated polynucleotide comprising a nucleic acid encoding an immunoglobulin heavy chain variable region (VH) selected from the group consisting of SEQ ID NOs: 173 to 184, 370, 374, 378 and 382, as shown in Table 7, or at least 80%, 85%, 90% or 95% identical to said SEQ ID NOs: 173 to 184, 370, 374, 378 and 382, as shown in Table 7. 10020] Other embodiments of the invention include, an isolated polynucleotide comprising a nucleic acid encoding an immunoglobulin light chain variable region (VL) selected from the group consisting of SEQ ID NOs: 185 to 194, 371, 375, 379 and 383, as shown in Table 9, or at least 80%, 85%, 90% or 95% identical to said SEQ ID NOs: 185 to 194, 371, 375, 379 and 383, as shown in Table 9. [0021] In certain embodiments, the invention includes compositions comprising the antibodies or antigen binding fragments described herein. [0022] In additional embodiments, the invention includes methods for treating CNS injury, ALS, Huntington's disease, Alzheimer's disease, Parkinson's disease, diabetic neuropathy and stroke comprising administering to an animal in need of said treatment an effective amount of an agent selected from the group consisting of an isolated Sp35 antibody or fragment thereof or compositions comprising said antibody or fragment thereof. [0023] In other emodiments, the invention includes methods for treating disease or disorders associated with inhibition of oligodendrocyte growth or differentiation; demyelination or dysmyelination of CNS neurons including multiple sclerosis (MS), progressive multifocal leukoencephalopathy (PML), encephalomyelitis (EPL), central pontine myelolysis (CPM), Wallerian Degeneration, adrenoleukodystrophy, Alexander's disease, and Pelizaeus Merzbacher disease (PMZ) by adminstering to an animal in need of said treatment an effective amount of an agent selected from the group consisting of an isolated Sp35 antibody or fragment thereof or compositions comprising said antibody or fragment thereof. [0024] Other embodiments of the present invention include a method of inhibiting signal transduction by Nogo receptor 1 (NgRI), comprising contacting the NgR1 with an effective amount of an agent selected from the group consisting of the isolated Sp35 antibody or fragment thereof or compositions comprising said antibody or fragment thereof. [00251 Additional embodiments of the present invention include a method of decreasing inhibition of axonal growth of a central nervous system (CNS) neuron, comprising contacting the neuron with an -5 effective amount of an agent selected from the group consisting of the isolated Sp35 antibody or fragment thereof of or compositions comprising said antibody or fragment thereof. [0026] Other embodiments of the present invention include a method of inhibiting growth cone collapse of a CNS neuron, comprising contacting the neuron with an effective amount of an agent selected from the group consisting of the isolated Sp35 antibody or fragment thereof or compositions comprising said antibody or fragment thereof. BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES [0027] FIG. 1: SDS-PAGE gel showing immunoprecipitation of Sp35 by monoclonal antibodies 1A7 and 2F3. [0028] FIG.2: FACS result showing that MAbs 1A7 and 2F3 bound to COS-7 or 293 cells expressing Sp35, but not to control cells with no Sp35 expression. [00291 FIG.3: MAbs 1A7 and 2F3 protected DRG neurons from myelin-mediated inhibition of neurite outgrowth. [00301 FIG.4A-G: Immunohistochemical staining ("IHC") of cocultures of DRG neurons and oligodendrocytes treated with monoclonal antibodies 1A7 and 2F3, or control antibody. Panels D and E are enlargements of panels B and C, respectively. Staining with anti-BII-tubulin antibody to identify axons, or anti-MBP antibody to identify oligodendrocytes. F: Quantitation of MBP+ myelinating cells upon treatment of cocultures with 1A7 or 2F3. G: Western blot analysis to quantify the MBP produced from cocultures of DRG neurons and oligodendrocytes treated with monoclonal antibodies 1A7 and 2F3. 100311 FIG. 5A-C: A: CC1 antibody staining of mouse oligodendrocytes in cuprizone model. B. Anti-MBP protein antibody or luxol fast blue staining of mouse neurons in cuprizone model. C: Quantitation of CC1 antibody-positive oligodendrocytes at four weeks and 6 weeks. [0032] FIG. 6: Surviving RGCs. Treatment with monoclonal antibody 1A7 Anti-Sp35 antibody 1A7 treated animals showed significant neuronal survival (80%) when compared to control-antibody or PBS treated animals, which each only showed approximately 50% neuronal survival. [0033] FIG. 7. BBB scores of mice receiving anti-Sp35 antibody 1A7 after spinal cord injury as described in Example 8. [0034) FIG. 8. Western blot of co-cultured oligodendrocytes and DRGs after incubation with anti Sp35 antibodies Li05, Li06 and 3, 10 and 30 mg of Sp35-Fc (LINGO-1-Ig) as described in Example 9. [00351 FIG. 9. Photographs of the optic nerves of A) Normal Rats; B) Myelin Oligodendrocyte Glycoprotein (MOG) induced Experimental Autoimnune Encephalomyelitis (EAE) rats; and C) Myelin Oligodendrocyte Glycoprotein (MOG) induced Experimental Autoimmune Encephalomyelitis -6 (EAE) rats treated with the Sp35 antibody 1A7. Electron micrographs of each optic nerve are shown below each photograph of the optic nerve. [00361 FIG. 10. Graph of the number of regenerative neuronal fibers per section counted in animals receiving an intravitreal injection of the Sp35 antibody 1A7 after optic nerve crush. DETAILED DESCRIPTION OF THE INVENTION I. DEFINITIONS 100371 It is to be noted that the term "a" or "an" entity refers to one or more of that entity; for example, "an Sp35 antibody," is understood to represent one or more Sp35 antibodies. As such, the terms "a" (or "an"), "one or more," and "at least one" can be used interchangeably herein. [0038] As used herein, the term "polypeptide" is intended to encompass a singular "polypeptide" as well as plural "polypeptides," and refers to a molecule composed of monomers (amino acids) linearly linked by amide bonds (also known as peptide bonds). The term "polypeptide" refers to any chain or chains of two or more amino acids, and does not refer to a specific length of the product. Thus, peptides, dipeptides, tripeptides, oligopeptides, "protein," "amino acid chain," or any other term used to refer to a chain or chains of two or more amino acids, are included within the definition of "polypeptide," and the term "polypeptide" may be used instead of, or interchangeably with any of these terms. The term "polypeptide" is also intended to refer to the products of post-expression modifications of the polypeptide, including without limitation glycosylation, acetylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, or modification by non naturally occurring amino acids. A polypeptide may be derived from a natural biological source or produced by recombinant technology, but is not necessarily translated from a designated nucleic acid sequence. It may be generated in any manner, including by chemical synthesis. 100391 A polypeptide of the invention may be of a size of about 3 or more, 5 or more, 10 or more, 20 or more, 25 or more, 50 or more, 75 or more, 100 or more, 200 or more, 500 or more, 1,000 or more, or 2,000 or more amino acids. Polypeptides may have a defined three-dimensional structure, although they do not necessarily have such structure. Polypeptides with a defined three-dimensional structure are referred to as folded, and polypeptides which do not possess a defined three-dimensional structure, but rather can adopt a large number of different conformations, and are referred to as unfolded. As used herein, the term glycoprotein refers to a protein coupled to at least one carbohydrate moiety that is attached to the protein via an oxygen-containing or a nitrogen-containing side chain of an amino acid residue, e.g., a serine residue or an asparagine residue. [0040] By an "isolated" polypeptide or a fragment, variant, or derivative thereof is intended a polypeptide that is not in its natural milieu. No particular level of purification is required. For example, an isolated polypeptide can be removed from its native or natural environment.

-7 Recombinantly produced polypeptides and proteins expressed in host cells are considered isolated for purposed of the invention, as are native or recombinant polypeptides which have been separated, fractionated, or partially or substantially purified by any suitable technique. [00411 Also included as polypeptides of the present invention are fragments, derivatives, analogs, or variants of the foregoing polypeptides, and any combination thereof. The terms "fragment," "variant," "derivative" and "analog" when referring to Sp35 antibodies or antibody polypeptides of the present invention include any polypeptides which retain at least some of the antigen-binding properties of the corresponding native antibody or polypeptide. Fragments of polypeptides of the present invention include proteolytic fragments, as well as deletion fragments, in addition to specific antibody fragments discussed elsewhere herein. Variants of Sp35 antibodies and antibody polypeptides of the present invention include fragments as described above, and also polypeptides with altered amino acid sequences due to amino acid substitutions, deletions, or insertions. Variants may occur naturally or be non-naturally occurring Non-naturally occurring variants may be produced using art-known mutagenesis techniques. Variant polypeptides may comprise conservative or non-conservative amino acid substitutions, deletions or additions. Derivatives of Sp35 antibodies and antibody polypeptides of the present invention, are polypeptides which have been altered so as to exhibit additional features not found on the native polypeptide. Examples include fusion proteins. Variant polypeptides may also be referred to herein as "polypeptide analogs." As used herein a "derivative" of an Sp35 antibody or antibody polypeptide refers to a subject polypeptide having one or more residues chemically derivatized by reaction of a functional side group. Also included as "derivatives" are those peptides which contain one or more naturally occurring amino acid derivatives of the twenty standard amino acids. For example, 4-hydroxyproline may be substituted for proline; 5-hydroxylysine may be substituted for lysine; 3-methylhistidine may be substituted for histidine; homoserine may be substituted for seine; and ornithine may be substituted for lysine. [0042] The term "polynucleotide" is intended to encompass a singular nucleic acid as well as plural nucleic acids, and refers to an isolated nucleic acid molecule or construct, e.g., messenger RNA (mRNA) or plasmid DNA (pDNA). A polynucleotide may comprise a conventional phosphodiester bond or a non-conventional bond (e.g., an amide bond, such as found in peptide nucleic acids (PNA)). The term "nucleic acid" refer to any one or more nucleic acid segments, e.g., DNA or RNA fragments, present in a polynucleotide. By "isolated" nucleic acid or polynucleotide is intended a nucleic acid molecule, DNA or RNA, which has been removed from its native environment. For example, a recombinant polynucleotide encoding an Sp35 antibody contained in a vector is considered isolated for the purposes of the present invention. Further examples of an isolated polynucleotide include recombinant polynucleotides maintained in heterologous host cells or purified (partially or substantially) polynucleotides in solution. Isolated RNA molecules include in vivo or in vitro RNA transcripts of polynucleotides of the present invention. Isolated polynucleotides or nucleic acids -8 according to the present invention further include such molecules produced synthetically. In addition, polynucleotide or a nucleic acid may be or may include a regulatory element such as a promoter, ribosome binding site, or a transcription terminator. [0043] As used herein, a "coding region" is a portion of nucleic acid which consists of codons translated into amino acids. Although a "stop codon" (TAG, TGA, or TAA) is not translated into an amino acid, it may be considered to be part of a coding region, but any flanking sequences, for example promoters, ribosome binding sites, transcriptional terminators, introns, and the like, are not part of a coding region. Two or more coding regions of the present invention can be present in a single polynucleotide construct, e.g., on a single vector, or in separate polynucleotide constructs, e.g., on separate (different) vectors. Furthermore, any vector may contain a single coding region, or may comprise two or more coding regions, e.g., a single vector may separately encode an immunoglobulin heavy chain variable region and an immunoglobulin light chain variable region. In addition, a vector, polynucleotide, or nucleic acid of the invention may encode heterologous coding regions, either fused or unfused to a nucleic acid encoding an Sp35 antibody or fragment, variant, or derivative thereof. Heterologous coding regions include without limitation specialized elements or motifs, such as a secretory signal peptide or a heterologous functional domain. [00441 In certain embodiments, the polynucleotide or nucleic acid is DNA. In the case of DNA, a polynucleotide comprising a nucleic acid which encodes a polypeptide normally may include a promoter and/or other transcription or translation control elements operably associated with one or more coding regions. An operable association is when a coding region for a gene product, e.g., a polypeptide, is associated with one or more regulatory sequences in such a way as to place expression of the gene product under the influence or control of the regulatory sequence(s). Two DNA fragments (such as a polypeptide coding region and a promoter associated therewith) are "operably associated" if induction of promoter function results in the transcription of mRNA encoding the desired gene product and if the nature of the linkage between the two DNA fragments does not interfere with the ability of the expression regulatory sequences to direct the expression of the gene product or interfere with the ability of the DNA template to be transcribed. Thus, a promoter region would be operably associated with a nucleic acid encoding a polypeptide if the promoter was capable of effecting transcription of that nucleic acid. The promoter may be a cell-specific promoter that directs substantial transcription of the DNA only in predetermined cells. Other transcription control elements, besides a promoter, for example enhancers, operators, repressors, and transcription termination signals, can be operably associated with the polynucleotide to direct cell-specific transcription. Suitable promoters and other transcription control regions are disclosed herein. [0045] A variety of transcription control regions are known to those skilled in the art. These include, without limitation, transcription control regions which function in vertebrate cells, such as, but not limited to, promoter and enhancer segments from cytomegaloviruses (the immediate early -9 promoter, in conjunction with intron-A), simian virus 40 (the early promoter), and retroviruses (such as Rous sarcoma virus). Other transcription control regions include those derived from vertebrate genes such as actin, heat shock protein, bovine growth hormone and rabbit B-globin, as well as other sequences capable of controlling gene expression in eukaryotic cells. Additional suitable transcription control regions include tissue-specific promoters and enhancers as well as lymphokine-inducible promoters (e.g., promoters inducible by interferons or interleukins). 100461 Similarly, a variety of translation control elements are known to those of ordinary skill in the art. These include, but are not limited to ribosome binding sites, translation initiation and termination codons, and elements derived from picomaviruses (particularly an internal ribosome entry site, or IRES, also referred to as a CITE sequence). [0047] In other embodiments, a polynucleotide of the present invention is RNA, for example, in the form of messenger RNA (mRNA). 10048] Polynucleotide and nucleic acid coding regions of the present invention may be associated with additional coding regions which encode secretory or signal peptides, which direct the secretion of a polypeptide encoded by a polynucleotide of the present invention. According to the signal hypothesis, proteins secreted by mammalian cells have a signal peptide or secretory leader sequence which is cleaved from the mature protein once export of the growing protein chain across the rough endoplasmic reticulum has been initiated. Those of ordinary skill in the art are aware that polypeptides secreted by vertebrate cells generally have a signal peptide fused to the N-terminus of the polypeptide, which is cleaved from the complete or "full length" polypeptide to produce a secreted or "mature" form of the polypeptide. In certain embodiments, the native signal peptide, e.g., an immunoglobulin heavy chain or light chain signal peptide is used, or a functional derivative of that sequence that retains the ability to direct the secretion of the polypeptide that is operably associated with it. Alternatively, a heterologous mammalian signal peptide, or a functional derivative thereof, may be used. For example, the wild-type leader sequence may be substituted with the leader sequence of human tissue plasminogen activator (TPA) or mouse B-glucuronidase. [0049] The present invention is directed to certain Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof. Unless specifically referring to full-sized antibodies such as naturally occurring antibodies, the term "Sp35 antibodies" encompasses full-sized antibodies as well as antigen binding fragments, variants, analogs, or derivatives of such antibodies, e.g., naturally occurring antibody or immunoglobulin molecules or engineered antibody molecules or fragments that bind antigen in a manner similar to antibody molecules. [00501 The terms "antibody" and "immunoglobulin" are used interchangeably herein. An antibody or immunoglobulin comprises at least the variable domain of a heavy chain, and normally comprises at least the variable domains of a heavy chain and a light chain. Basic immunoglobulin structures in -10 vertebrate systems are relatively well understood. See, e.g., Harlow et al., Antibodies: A Laboratory Manual, (Cold Spring Harbor Laboratory Press, 2nd ed. 1988). [00511 As will be discussed in more detail below, the term "immunoglobulin" comprises various broad classes of polypeptides that can be distinguished biochemically. Those skilled in the art will appreciate that heavy chains are classified as gamma, mu, alpha, delta, or epsilon, (y, p, a, 8, s) with some subclasses among them (e.g., yl-y4). It is the nature of this chain that determines the "class" of the antibody as IgG, IgM, IgA IgG, or IgE, respectively. The immunoglobulin subclasses (isotypes) e.g., IgG 1 , IgG 2 , IgG 3 , IgG4, IgAI, etc. are well characterized and are known to confer functional specialization. Modified versions of each of these classes and isotypes are readily discernable to the skilled artisan in view of the instant disclosure and, accordingly, are within the scope of the instant invention. All immunoglobulin classes are clearly within the scope of the present invention, the following discussion will generally be directed to the IgG class of immunoglobulin molecules. With regard to IgG, a standard immunoglobulin molecule comprises two identical light chain polypeptides of molecular weight approximately 23,000 Daltons, and two identical heavy chain polypeptides of molecular weight 53,000-70,000. The four chains are typically joined by disulfide bonds in a "Y" configuration wherein the light chains bracket the heavy chains starting at the mouth of the "Y" and continuing through the variable region. [00521 Light chains are classified as either kappa or lambda (1c, X). Each heavy chain class may be bound with either a kappa or lambda light chain. In general, the light and heavy chains are covalently bonded to each other, and the "tail" portions of the two heavy chains are bonded to each other by covalent disulfide linkages or non-covalent linkages when the immunoglobulins are generated either by hybridomas, B cells or genetically engineered host cells. In the heavy chain, the amino acid sequences run from an N-terminus at the forked ends of the Y configuration to the C-terminus at the bottom of each chain. [00531 Both the light and heavy chains are divided into regions of structural and functional homology. The terms "constant" and "variable" are used functionally. In this regard, it will be appreciated that the variable domains of both the light (VL) and heavy (VH) chain portions determine antigen recognition and specificity. Conversely, the constant domains of the light chain (CL) and the heavy chain (CH1, CH2 or CH 3 ) confer important biological properties such as secretion, transplacental mobility, Fc receptor binding, complement binding, and the like. By convention the numbering of the constant region domains increases as they become more distal from the antigen binding site or amino terminus of the antibody. The N-terminal portion is a variable region and at the C-terminal portion is a constant region; the CH3 and CL domains actually comprise the carboxy-terminus of the heavy and light chain, respectively. [0054] As indicated above, the variable region allows the antibody to selectively recognize and specifically bind epitopes on antigens. That is, the VL domain and VH domain, or subset of the - 11 complementarity determining regions (CDRs), of an antibody combine to form the variable region that defines a three dimensional antigen binding site. This quaternary antibody structure forms the antigen binding site present at the end of each arm of the Y. More specifically, the antigen binding site is defined by three CDRs on each of the VH and V chains. In some instances, e.g., certain immunoglobulin molecules derived from camelid species or engineered based on camelid immunoglobulins, a complete inimunoglobulin molecule may consist of heavy chains only, with no light chains. See, e.g., Hamers-Casterman et al., Nature 363:446-448 (1993). [00551 In naturally occurring antibodies, the six "complementarity determining regions" or "CDRs" present in each antigen binding domain are short, non-contiguous sequences of amino acids that are specifically positioned to form the antigen binding domain as the antibody assumes its three dimensional configuration in an aqueous environment. The remainder of the amino acids in the antigen binding domains, referred to as "framework" regions, show less inter-molecular variability. The framework regions largely adopt a p-sheet conformation and the CDRs form loops which connect, and in some cases form part of, the P-sheet structure. Thus, framework regions act to form a scaffold that provides for positioning the CDRs in correct orientation by inter-chain, non-covalent interactions. The antigen binding domain formed by the positioned CDRs defines a surface complementary to the epitope on the immunoreactive antigen. This complementary surface promotes the non-covalent binding of the antibody to its cognate epitope. The amino acids comprising the CDRs and the framework regions, respectively, can be readily identified for any given heavy or light chain variable region by one of ordinary skill in the art, since they have been precisely defined (see, "Sequences of Proteins of Immunological Interest," Kabat, E., et al., U.S. Department of Health and Human Services, (1983); and Chothia and Lesk, J. Mol. Biol., 196:901-917 (1987), which are incorporated herein by reference in their entireties). [0056] In the case where there are two or more definitions of a term which is used and/or accepted within the art, the definition of the term as used herein is intended to include all such meanings unless explicitly stated to the contrary. A specific example is the use of the term "complementarity determining region" ("CDR") to describe the non-contiguous antigen combining sites found within the variable region of both heavy and light chain polypeptides. This particular region has been described by Kabat et al., U.S. Dept. of Health and Human Services, "Sequences of Proteins of Immunological Interest" (1983) and by Chothia et al., J. Mol. Biol. 196:901-917 (1987), which are incorporated herein by reference, where the definitions include overlapping or subsets of amino acid residues when compared against each other. Nevertheless, application of either definition to refer to a CDR of an antibody or variants thereof is intended to be within the scope of the term as defined and used herein. The appropriate amino acid residues which encompass the CDRs as defined by each of the above cited references are set forth below in Table I as a comparison. The exact residue numbers which encompass a particular CDR will vary depending on the sequence and size of the CDR. Those skilled in the art can -12 routinely determine which residues comprise a particular CDR given the variable region amino acid sequence of the antibody. TABLE 1. CDR Definitions' Kabat Chothia VH CDRI 31-35 26-32 VH CDR2 50-65 52-58 VH CDR3 95-102 95-102 VL CDR1 24-34 26-32 VL CDR2 50-56 50-52 VL CDR3 89-97 91-96 'Numbering of all CDR definitions in Table 1 is according to the numbering conventions set forth by Kabat et al. (see below). [00571 Kabat et al. also defined a numbering system for variable domain sequences that is applicable to any antibody. One of ordinary skill in the art can unambigously assign this system of "Kabat numbering" to any variable domain sequence, without reliance on any experimental data beyond the sequence itself. As used herein, "Kabat numbering" refers to the numbering system set forth by Kabat et al., U.S. Dept. of Health and Human Services, "Sequence of Proteins of Immunological Interest" (1983). Unless otherwise specified, references to the numbering of specific amino acid residue positions in an Sp35 antibody or antigen-binding fragment, variant, or derivative thereof of the present invention are according to the Kabat numbering system. [00581 In camelid species, the heavy chain variable region, referred to as VHH, forms the entire antigen-binding domain. The main differences between camelid VHH variable regions and those derived from conventional antibodies (VHf) include (a) more hydrophobic amino acids in the light chain contact surface of VH as compared to the corresponding region in VHH, (b) a longer CDR3 in VHH, and (c) the frequent occurrence of a disulfide bond between CDR1 and CDR3 in VHH. [0059] Antibodies or antigen-binding fragments, variants, or derivatives thereof of the invention include, but are not limited to, polyclonal, monoclonal, multispecific, human, humanized, primatized, or chimeric antibodies, single chain antibodies, epitope-binding fragments, e.g., Fab, Fab' and F(ab') 2 , Fd, Fvs, single-chain Fvs (scFv), single-chain antibodies, disulfide-linked Fvs (sdFv), fragments comprising either a VL or VH domain, fragments produced by a Fab expression library, and anti idiotypic (anti-Id) antibodies (including, e.g., anti-Id antibodies to Sp35 antibodies disclosed herein). ScFv molecules are known in the art and are described, e.g., in US patent 5,892,019. Inmunoglobulin or antibody molecules of the invention can be of any type (e.g., IgG, IgE, IgM, IgD, IgA, and IgY), class (e.g., IgG1, IgG2, IgG3, IgG4, IgAl and IgA2) or subclass of immunoglobulin molecule. [0060] Antibody fragments, including single-chain antibodies, may comprise the variable region(s) alone or in combination with the entirety or a portion of the following: hinge region, CHI, CH 2 , and CH 3 domains. Also included in the invention are antigen-binding fragments also comprising any - 13 combination of variable region(s) with a hinge region, CH1, CH2, and CH 3 domains. Antibodies or immunospecific fragments thereof for use in the diagnostic and therapeutic methods disclosed herein may be from any animal origin including birds and mammals. Preferably, the antibodies are human, murine, donkey, rabbit, goat, guinea pig, camel, llama, horse, or chicken antibodies. In another embodiment, the variable region may be condricthoid in origin (e.g., from sharks). As used herein, "human" antibodies include antibodies having the amino acid sequence of a human immunoglobulin and include antibodies isolated from human immunoglobulin libraries or from animals transgenic for one or more human immunoglobulins and that do not express endogenous immunoglobulins, as described infra and, for example in, U.S. Pat. No. 5,939,598 by Kucherlapati et al. [00611 As used herein, the term "heavy chain portion" includes amino acid sequences derived from an immunoglobulin heavy chain. A polypeptide comprising a heavy chain portion comprises at least one of: a CH1 domain, a hinge (e.g., upper, middle, and/or lower hinge region) domain, a CH2 domain, a CH3 domain, or a variant or fragment thereof. For example, a binding polypeptide for use in the invention may comprise a polypeptide chain comprising a CH1 domain; a polypeptide chain comprising a CH1 domain, at least a portion of a hinge domain, and a CH 2 domain; a polypeptide chain comprising a CH1 domain and a CH3 domain; a polypeptide chain comprising a CH1 domain, at least a portion of a hinge domain, and a CH3 domain, or a polypeptide chain comprising a CHI domain, at least a portion of a hinge domain, a CH 2 domain, and a CH 3 domain. In another embodiment, a polypeptide of the invention comprises a polypeptide chain comprising a CH3 domain. Further, a binding polypeptide for use in the invention may lack at least a portion of a CH 2 domain (e.g., all or part of a CH2 domain). As set forth above, it will be understood by one of ordinary skill in the art that these domains (e.g., the heavy chain portions) may be modified such that they vary in amino acid sequence from the naturally occurring immunoglobulin molecule. [00621 In certain Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof disclosed herein, the heavy chain portions of one polypeptide chain of a multimer are identical to those on a second polypeptide chain of the multimer. Alternatively, heavy chain portion-containing monomers of the invention are not identical. For example, each monomer may comprise a different target binding site, forming, for example, a bispecific antibody. [00631 The heavy chain portions of a binding polypeptide for use in the diagnostic and treatment methods disclosed herein may be derived from different immunoglobulin molecules. For example, a heavy chain portion of a polypeptide may comprise a CH1 domain derived from an IgGl molecule and a hinge region derived from an IgG3 molecule. In another example, a heavy chain portion can comprise a hinge region derived, in part, from an IgGI molecule and, in part, from an IgG3 molecule. In another example, a heavy chain portion can comprise a chimeric hinge derived, in part, from an IgG1 molecule and, in part, from an IgG4 molecule.

-14 [0064] As used herein, the term "light chain portion" includes amino acid sequences derived from an immunoglobulin light chain. Preferably, the light chain portion comprises at least one of a VL or CL domain. [0065] Sp 3 5 antibodies, or antigen-binding fragments, variants, or derivatives thereof disclosed herein may be described or specified in terms of the epitope(s) or portion(s) of an antigen, e.g., a target polypeptide (Sp35) that they recognize or specifically bind. The portion of a target polypeptide which specifically interacts with the antigen binding domain of an antibody is an "epitope," or an "antigenic determinant." A target polypeptide may comprise a single epitope, but typically comprises at least two epitopes, and can include any number of epitopes, depending on the size, conformation, and type of antigen. Furthermore, it should be noted that an "epitope" on a target polypeptide may be or include non-polypeptide elements, e.g., an "epitope may include a carbohydrate side chain. [00661 The minimum size of a peptide or polypeptide epitope for an antibody is thought to be about four to five amino acids. Peptide or polypeptide epitopes preferably contain at least seven, more preferably at least nine and most preferably between at least about 15 to about 30 amino acids. Since a CDR can recognize an antigenic peptide or polypeptide in its tertiary form, the amino acids comprising an epitope need not be contiguous, and in some cases, may not even be on the same peptide chain. In the present invention, peptide or polypeptide epitope recognized by Sp35 antibodies of the present invention contains a sequence of at least 4, at least 5, at least 6, at least 7, more preferably at least 8, at least 9, at least 10, at least 15, at least 20, at least 25, or between about 15 to about 30 contiguous or non-contiguous amino acids of Sp35. [0067] By "specifically binds," it is generally meant that an antibody binds to an epitope via its antigen binding domain, and that the binding entails some complementarity between the antigen binding domain and the epitope. According to this definition, an antibody is said to "specifically bind" to an epitope when it binds to that epitope, via its antigen binding domain more readily than it would bind to a random, unrelated epitope. The term "specificity" is used herein to qualify the relative affinity by which a certain antibody binds to a certain epitope. For example, antibody "A" may be deemed to have a higher specificity for a given epitope than antibody "B," or antibody "A" may be said to bind to epitope "C" with a higher specificity than it has for related epitope "D." [00681 By "preferentially binds," it is meant that the antibody specifically binds to an epitope more readily than it would bind to a related, similar, homologous, or analogous epitope. Thus, an antibody which "preferentially binds" to a given epitope would more likely bind to that epitope than to a related epitope, even though such an antibody may cross-react with the related epitope. [00691 By way of non-limiting example, an antibody may be considered to bind a first epitope preferentially if it binds said first epitope with a dissociation constant (KD) that is less than the antibody's KD for the second epitope. In another non-limiting example, an antibody may be considered to bind a first antigen preferentially if it binds the first epitope with an affinity that is at least one order -15 of magnitude less than the antibody's KD for the second epitope. In another non-limiting example, an antibody may be considered to bind a first epitope preferentially if it binds the first epitope with an affinity that is at least two orders of magnitude less than the antibody's KD for the second epitope. [0070] In another non-limiting example, an antibody may be considered to bind a first epitope preferentially if it binds the first epitope with an off rate (k(off)) that is less than the antibody's k(off) for the second epitope. In another non-limiting example, an antibody may be considered to bind a first epitope preferentially if it binds the first epitope with an affinity that is at least one order of magnitude less than the antibody's k(off) for the second epitope. In another non-limiting example, an antibody may be considered to bind a first epitope preferentially if it binds the first epitope with an affinity that is at least two orders of magnitude less than the antibody's k(off) for the second epitope. [00711 An antibody or or antigen-binding fragment, variant, or derivative disclosed herein may be said to bind a target polypeptide disclosed herein or a fragment or variant thereof with an off rate (k(off)) of less than or equal to 5 X 10- sec', 102 sec-, 5 X 10-3 sec 1 or 10-3 sec'. More preferably, an antibody of the invention may be said to bind a target polypeptide disclosed herein or a fragment or variant thereof with an off rate (k(off)) less than or equal to 5 X 104 sec-, 104 sec-, 5 X 10- sec', or 10-5 sec' 5 X 10-6 sec-, 10-4 sec, 5 X 104 sec' or 10- sec'. [00721 An antibody or or antigen-binding fragment, variant, or derivative disclosed herein may be said to bind a target polypeptide disclosed herein or a fragment or variant thereof with an on rate (k(on)) of greater than or equal to 103 M 4 sec', 5 X 103 1W sec, 104 1 sec7' or 5 X 104 M ' sec'. More preferably, an antibody of the invention may be said to bind a target polypeptide disclosed herein or a fragment or variant thereof with an on rate (k(on)) greater than or equal to 105 M-' sec-, 5 X 105 1W sec-, 10" M7 1 sec-, or 5 X 106 M1 sec- or 107 M 4 sec-. [00731 An antibody is said to competitively inhibit binding of a reference antibody to a given epitope if it preferentially binds to that epitope to the extent that it blocks, to some degree, binding of the reference antibody to the epitope. Competitive inhibition may be determined by any method known in the art, for example, competition ELISA assays. An antibody may be said to competitively inhibit binding of the reference antibody to a given epitope by at least 90%, at least 80%, at least 70%, at least 60%, or at least 50%. [0074] As used herein, the term "affinity" refers to a measure of the strength of the binding of an individual epitope with the CDR of an immunoglobulin molecule. See, e.g., Harlow et al., Antibodies: A Laboratory Manual, (Cold Spring Harbor Laboratory Press, 2nd ed. 1988) at pages 27-28. As used herein, the term "avidity" refers to the overall stability of the complex between a population of immunoglobulins and an antigen, that is, the functional combining strength of an immunoglobulin mixture with the antigen. See, e.g. , Harlow at pages 29-34. Avidity is related to both the affinity of individual immunoglobulin molecules in the population with specific epitopes, and also the valencies of the immunoglobulins and the antigen. For example, the interaction between a bivalent monoclonal -16 antibody and an antigen with a highly repeating epitope structure, such as a polymer, would be one of high avidity. [0075] Sp35 antibodies or antigen-binding fragments, variants or derivatives thereof of the invention may also be described or specified in terms of their cross-reactivity. As used herein, the term "cross-reactivity" refers to the ability of an antibody, specific for one antigen, to react with a second antigen; a measure of relatedness between two different antigenic substances. Thus, an antibody is cross reactive if it binds to an epitope other than the one that induced its formation. The cross reactive epitope generally contains many of the same complementary structural features as the inducing epitope, and in some cases, may actually fit better than the original. [0076] For example, certain antibodies have some degree of cross-reactivity, in that they bind related, but non-identical epitopes, e.g., epitopes with at least 95%, at least 90%, at least 85%, at least 80%, at least 75%, at least 70%, at least 65%, at least 60%, at least 55%, and at least 50% identity (as calculated using methods known in the art and described herein) to a reference epitope. An antibody may be said to have little or no cross-reactivity if it does not bind epitopes with less than 95%, less than 90%, less than 85%, less than 80%, less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, and less than 50% identity (as calculated using methods known in the art and described herein) to a reference epitope. An antibody may be deemed "highly specific" for a certain epitope, if it does not bind any other analog, ortholog, or homolog of that epitope. 10077] Sp35 antibodies or antigen-binding fragments, variants or derivatives thereof of the invention may also be described or specified in terms of their binding affinity to a polypeptide of the invention. Preferred binding affinities include those with a dissociation constant or Kd less than 5 x 102 M, 10 2 M, 5 x 10 3 M, 104 M, 5 x 104M, 10~4 M, 5 x 10-5 M, 10 5 M, 5 x 106 M, 106 M, 5 x 10-7 M, 10 M, 5 x 10-'M, 10~"M, 5 x 10 9 M, 10- 9 M, 5 x 10 10 M, 10-10 M, 5 x 10~ 1 M, 10-11 M, 5 x 10- 12 M, 10 12 M, 5 x 10 13 M, 10- 3 M, 5 x 10 14 M, 1014 M, 5 x 10 5 M, or 10- 15 M. [00781 Sp35 antibodies or antigen-binding fragments, variants or derivatives thereof of the invention may be "multispecific," e.g., bispecific, trispecific or of greater multispecificity, meaning that it recognizes and binds to two or more different epitopes present on one or more different antigens (e.g., proteins) at the same time. Thus, whether an Sp35 antibody is "monospecfic" or "multispecific," e.g., "bispecific," refers to the number of different epitopes with which a binding polypeptide reacts. Multispecific antibodies may be specific for different epitopes of a target polypeptide described herein or may be specific for a target polypeptide as well as for a heterologous epitope, such as a heterologous polypeptide or solid support material. [0079] As used herein the term "valency" refers to the number of potential binding domains, e.g., antigen binding domains, present in an Sp35 antibody, binding polypeptide or antibody. Each binding domain specifically binds one epitope. When an Sp35 antibody, binding polypeptide or antibody comprises more than one binding domain, each binding domain may specifically bind the same epitope, -17 for an antibody with two binding domains, termed "bivalent monospecific," or to different epitopes, for an antibody with two binding domains, termed "bivalent bispecific." An antibody may also be bispecific and bivalent for each specificity (termed "bispecific tetravalent antibodies"). In another embodiment, tetravalent minibodies or domain deleted antibodies can be made. [00801 Bispecific bivalent antibodies, and methods of making them, are described, for instance in U.S. Patent Nos. 5,731,168; 5,807,706; 5,821,333; and U.S. Appl. Publ. Nos. 2003/020734 and 2002/0155537, the disclosures of all of which are incoporated by reference herein. Bispecific tetravalent antibodies, and methods of making them are described, for instance, in WO 02/096948 and WO 00/44788, the disclosures of both of which are incorporated by reference herein. See generally, PCT publications WO 93/17715; WO 92/08802; WO 91/00360; WO 92/05793; Tutt et al., J. Immunol. 147:60-69 (1991); U.S. Pat. Nos. 4,474,893; 4,714,681; 4,925,648; 5,573,920; 5,601,819; Kostelny et al., J. linmunol. 148:1547-1553 (1992). [00811 As previously indicated, the subunit structures and three dimensional configuration of the constant regions of the various immunoglobulin classes are well known. As used herein, the term "VH domain" includes the amino terminal variable domain of an immunoglobulin heavy chain and the term "Cal domain" includes the first (most amino terminal) constant region domain of an immunoglobulin heavy chain. The CH1 domain is adjacent to the VH domain and is amino terminal to the hinge region of an immunoglobulin heavy chain molecule. 100821 As used herein the term "CR 2 domain" includes the portion of a heavy chain molecule that extends, e.g., from about residue 244 to residue 360 of an antibody using conventional numbering schemes (residues 244 to 360, Kabat numbering system; and residues 231-340, EU numbering system; see Kabat EA et al. op. cit. The CR 2 domain is unique in that it is not closely paired with another domain. Rather, two N-linked branched carbohydrate chains are interposed between the two CH 2 domains of an intact native IgG molecule. It is also well documented that the CH3 domain extends from the CH 2 domain to the C-terminal of the IgG molecule and comprises approximately 108 residues. [00831 As used herein, the term "hinge region" includes the portion of a heavy chain molecule that joins the CHI domain to the CH 2 domain. This hinge region comprises approximately 25 residues and is flexible, thus allowing the two N-terminal antigen binding regions to move independently. Hinge regions can be subdivided into three distinct domains: upper, middle, and lower hinge domains (Roux et al., J. Immunol. 161:4083 (1998)). [0084] As used herein the term "disulfide bond" includes the covalent bond formed between two sulfur atoms. The amino acid cysteine comprises a thiol group that can form a disulfide bond or bridge with a second thiol group. In most naturally occurring IgG molecules, the CI and CL regions are linked by a disulfide bond and the two heavy chains are linked by two disulfide bonds at positions corresponding to 239 and 242 using the Kabat numbering system (position 226 or 229, EU numbering system).

-18 [00851 As used herein, the term "chimeric antibody" will be held to mean any antibody wherein the immunoreactive region or site is obtained or derived from a first species and the constant region (which may be intact, partial or modified in accordance with the instant invention) is obtained from a second species. In preferred embodiments the target binding region or site will be from a non-human source (e.g. mouse or primate) and the constant region is human. [0086] As used herein, the term "engineered antibody" refers to an antibody in which the variable domain in either the heavy and light chain or both is altered by at least partial replacement of one or more CDRs from an antibody of known specificity and, if necessary, by partial framework region replacement and sequence changing. Although the CDRs may be derived from an antibody of the same class or even subclass as the antibody from which the framework regions are derived, it is envisaged that the CDRs will be derived from an antibody of different class and preferably from an antibody from a different species. An engineered antibody in which one or more "donor" CDRs from a non-human antibody of known specificity is grafted into a human heavy or light chain framework region is referred to herein as a "humanized antibody." It may not be necessary to replace all of the CDRs with the complete CDRs from the donor variable region to transfer the antigen binding capacity of one variable domain to another. Rather, it may only be necessary to transfer those residues that are necessary to maintain the activity of the target binding site. Given the explanations set forth in, e.g., U. S. Pat. Nos. 5,585,089, 5,693,761, 5,693,762, and 6,180,370, it will be well within the competence of those skilled in the art, either by carrying out routine experimentation or by trial and error testing to obtain a functional engineered or humanized antibody. [0087] As used herein the term "properly folded polypeptide" includes polypeptides (e.g., Sp35 antibodies) in which all of the functional domains comprising the polypeptide are distinctly active. As used herein, the term "improperly folded polypeptide" includes polypeptides in which at least one of the functional domains of the polypeptide is not active. In one embodiment, a properly folded polypeptide comprises polypeptide chains linked by at least one disulfide bond and, conversely, an improperly folded polypeptide comprises polypeptide chains not linked by at least one disulfide bond. [00881 As used herein the term "engineered" includes manipulation of nucleic acid or polypeptide molecules by synthetic means (e.g. by recombinant techniques, in vitro peptide synthesis, by enzymatic or chemical coupling of peptides or some combination of these techniques). [0089] As used herein, the terms "linked," "fused" or "fusion" are used interchangeably. These terms refer to the joining together of two more elements or components, by whatever means including chemical conjugation or recombinant means. An "in-frame fusion" refers to the joining of two or more polynucleotide open reading frames (ORFs) to form a continuous longer ORF, in a manner that maintains the correct translational reading frame of the original ORFs. Thus, a recombinant fusion protein is a single protein containing two ore more segments that correspond to polypeptides encoded by the original ORFs (which segments are not normally so joined in nature.) Although the reading -19 frame is thus made continuous throughout the fused segments, the segments may be physically or spatially separated by, for example, in-frame linker sequence. For example, polynucleotides encoding the CDRs of an immunoglobulin variable region may be fused, in-frame, but be separated by a polynucleotide encoding at least one immunoglobulin framework region or additional CDR regions, as long as the "fused" CDRs are co-translated as part of a continuous polypeptide. [0090] In the context of polypeptides, a "linear sequence" or a "sequence" is an order of amino acids in a polypeptide in an amino to carboxyl terminal direction in which residues that neighbor each other in the sequence are contiguous in the primary structure of the polypeptide. [0091] The term "expression" as used herein refers to a process by which a gene produces a biochemical, for example, an RNA or polypeptide. The process includes any manifestation of the functional presence of the gene within the cell including, without limitation, gene knockdown as well as both transient expression and stable expression. It includes without limitation transcription of the gene into messenger RNA (mRNA), transfer RNA (tRNA), small hairpin RNA (shRNA), small interfering RNA (siRNA) or any other RNA product, and the translation of such mRNA into polypeptide(s). If the final desired product is a biochemical, expression includes the creation of that biochemical and any precursors. Expression of a gene produces a "gene product." As used herein, a gene product can be either a nucleic acid, e.g., a messenger RNA produced by transcription of a gene, or a polypeptide which is translated from a transcript. Gene products described herein further include nucleic acids with post transcriptional modifications, e.g., polyadenylation, or polypeptides with post translational modifications, e.g., methylation, glycosylation, the addition of lipids, association with other protein subunits, proteolytic cleavage, and the like. [00921 As used herein, the terms "treat" or "treatment" refer to both therapeutic treatment and prophylactic or preventative measures, wherein the object is to prevent or slow down (lessen) an undesired physiological change or disorder, such as the progression of multiple sclerosis. Beneficial or desired clinical results include, but are not limited to, alleviation of symptoms, diminishment of extent of disease, stabilized (i.e., not worsening) state of disease, delay or slowing of disease progression, amelioration or palliation of the disease state, and remission (whether partial or total), whether detectable or undetectable. "Treatment" can also mean prolonging survival as compared to expected survival if not receiving treatment. Those in need of treatment include those already with the condition or disorder as well as those prone to have the condition or disorder or those in which the condition or disorder is to be prevented. [00931 By "subject" or "individual" or "animal" or "patient" or "mammal," is meant any subject, particularly a mammalian subject, for whom diagnosis, prognosis, or therapy is desired. Mammalian subjects include humans, domestic animals, farm animals, and zoo, sports, or pet animals such as dogs, cats, guinea pigs, rabbits, rats, mice, horses, cattle, cows, and so on.

-20 [00941 As used herein, phrases such as "a subject that would benefit from administration of an Sp35 antibody" and "an animal in need of treatment" includes subjects, such as mammalian subjects, that would benefit from administration of an Sp35 antibody used, e.g., for detection of an Sp35 polypeptide (e.g., for a diagnostic procedure) and/or from treatment, i.e., palliation or prevention of a disease such as MS, with an Sp35 antibody. As described in more detail herein, the Sp35 antibody can be used in unconjugated form or can be conjugated, e.g., to a drug, prodrug, or an isotope. II. Sp35 100951 Naturally occurring human Sp35 (Sp35) is a glycosylated central nervous system-specific protein which is predicted to have 614 amino acids (SEQ ID NO: 2), including a 33 amino acid signal sequence. Sp 35 is also known in the art by the names LINGO-1, LRRN6, LRRN6A, FLJ14594, LERN1, MGC17422 and UNQ201. The human, full-length wild-type Sp35 polypeptide contains an LRR domain consisting of 14 leucine-rich repeats (including N- and C-terminal caps), an Ig domain, a transmembrane region, and a cytoplasmic domain. The cytoplasmic domain contains a canonical tyrosine phosphorylation site. In addition, the naturally occurring Sp35 protein contains a signal sequence, a short basic region between the LRRCT and Ig domain, and a transmembrane region between the Ig domain and the cytoplasmic domain. The human Sp35 gene (SEQ ID NO: 1) contains alternative translation start codons, so that six additional amino acids, i.e., MQVSKR (SEQ ID NO: 3) may or may not be present at the N-terminus of the Sp35 signal sequence. Table 2 lists the Sp35 domains and other regions, according to amino acid residue number, based on the Sp35 amino acid sequence presented herein as SEQ ID NO: 2. The Sp35 polypeptide is characterized in more detail in PCT Publication No. WO 2004/085648, which is incorporated herein by reference in its entirety. TABLE 2--Sp35 Domains Domain or Region Beginning Residue Ending Residue Signal Sequence 1 33 or 35 LRRNT 34 or 36 64 LRR 66 89 LRR 90 113 LRR 114 137 LRR 138 161 LRR 162 185 LRR 186 209 LRR 210 233 LRR 234 257 LRR 258 281 -21 LRR 282 305 LRR 306 329 LRR 330 353 LRRCT 363 414 or 416 Basic 415 or 417 424 Ig 419 493 Connecting sequence 494 551 Transmembrane 552 576 Cytoplasmic 577 614 [0096] Tissue distribution and developmental expression of Sp35 has been studied in humans and rats. Sp35 biology has been studied in an experimental animal (rat) model. Expression of rat Sp35 is localized to neurons and oligodendrocytes, as determined by northern blot and immuno-histochemical staining. Rat Sp35 mRNA expression level is regulated developmentally, peaking shortly after birth, i.e., ca. postnatal day one. In a rat spinal cord transection injury model, Sp35 is up-regulated at the injury site, as determined by RT-PCR. See Mi et al. Nature Neurosci. 7:221-228 (2004). [00971 In the context of the amino acids comprising the various structural and functional domains of an Sp35 polypeptide, the term "about" includes the particularly recited value and values larger or smaller by several (e.g., 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1) amino acids. Since the location of these domains as listed in Table 1 have been predicted by computer graphics, one of ordinary skill would appreciate that the amino acid residues constituting the domains may vary slightly (e.g., by about 1 to 15 residues) depending on the criteria used to define the domain. [00981 The inventors have discovered that full-length, wild-type Sp35 binds to NgR1. See PCT Publication No. WO 2004/085648. The inventors have also discovered that Sp35 is expressed in oligodendrocytes and that the Sp35 protein is involved in the regulation of oligodendrocyte-mediated myelination of axons. See U.S Patent Publication No. 2006/0009388 Al, which is incorporated herein by reference in its entirety. [00991 The nucleotide sequence for the full-length Sp35 molecule is as follows: ATGCTGGCGGGGGGCGTGAGGAGCATGCCCAGCCCCCTCCTGGCCTGCTGGCAGCCCATCCTCCTGCTGG TGCTGGGCTCAGTGCTGTCAGGCTCGGCCACGGGCTGCCCGCCCCGCTGCGAGTGCTCCGCCCAGGACCG CGCTGTGCTGTGCCACCGCAAGCGCTTTGTGGCAGTCCCCGAGGGCATCCCCACCGAGACGCGCCTGCTG GACCTAGGCAAGAACCGCATCAAAACGCTCAACCAGGACGAGTTCGCCAGCTTCCCGCACCTGGAGGAGC TGGAGCTCAACGAGAACATCGTGAGCGCCGTGGAGCCCGGCGCCTTCAACAACCTCTTCAACCTCCGGAC GCTGGGTCTCCGCAGCAACCGCCTGAAGCTCATCCCGCTAGGCGTCTTCACTGGCCTCAGCAACCTGACC AAGCTGGACATCAGCGAGAACAAGATTGTTATCCTGCTGGACTACATGTTTCAGGACCTGTACAACCTCA AGTCACTGGAGGTTGGCGACAATGACCTCGTCTACATCTCTCACCGCGCCTTCAGCGGCCTCAACAGCCT GGAGCAGCTGACGCTGGAGAAATGCAACCTGACCTCCATCCCCACCGAGGCGCTGTCCCACCTGCACGGC CTCATCGTCCTGAGGCTCCGGCACCTCAACATCAATGCCATCCGGGACTACTCCTTCAAGAGGCTCTACC GACTCAAGGTCTTGGAGATCTCCCACTGGCCCTACTTGGACACCATGACACCCAACTGCCTCTACGGCCT

CAACCTGACGTCCCTGTCCATCACACACTGCAATCTGACCGCTGTGCCCTACCTGGCCGTCCGCCACCTA

-22 GTCTATCTCCGCTTCCTCAACCTCTCCTACAACCCCATCAGCACCATTGAGGGCTCCATGTTGCATGAGC TGCTCCGGCTGCAGGAGATCCAGCTGGTGGGCGGGCAGCTGGCCGTGGTGGAGCCCTATGCCTTCCGCGG CCTCAACTACCTGCGCGTGCTCAATGTCTCTGGCAACCAGCTGACCACACTGGAGGAATCAGTCTTCCAC TCGGTGGGCAACCTGGAGACACTCATCCTGGACTCCAACCCGCTGGCCTGCGACTGTCGGCTCCTGTGGG TGTTCCGGCGCCGCTGGCGGCTCAACTTCAACCGGCAGCAGCCCACGTGCGCCACGCCCGAGTTTGTCCA GGGCAAGGAGTTCAAGGACTTCCCTGATGTGCTACTGCCCAACTACTTCACCTGCCGCCGCGCCCGCATC CGGGACCGCAAGGCCCAGCAGGTGTTTGTGGACGAGGGCCACACGGTGCAGTTTGTGTGCCGGGCCGATG GCGACCCGCCGCCCGCCATCCTCTGGCTCTCACCCCGAAAGCACCTGGTCTCAGCCAAGAGCAATGGGCG GCTCACAGTCTTCCCTGATGGCACGCTGGAGGTGCGCTACGCCCAGGTACAGGACAACGGCACGTACCTG TGCATCGCGGCCAACGCGGGCGGCAACGACTCCATGCCCGCCCACCTGCATGTGCGCAGCTACTCGCCCG ACTGGCCCCATCAGCCCAACAAGACCTTCGCTTTCATCTCCAACCAGCCGGGCGAGGGAGAGGCCAACAG CACCCGCGCCACTGTGCCTTTCCCCTTCGACATCAAGACCCTCATCATCGCCACCACCATGGGCTTCATC TCTTTCCTGGGCGTCGTCCTCTTCTGCCTGGTGCTGCTGTTTCTCTGGAGCCGGGGCAAGGGCAACACAA AGCACAACATCGAGATCGAGTATGTGCCCCGAAAGTCGGACGCAGGCATCAGCTCCGCCGACGCGCCCCG CAAGTTCAACATGAAGATGATATGA (SEQ ID NO: 1). [01001 The polypeptide sequence for the full-length Sp35 polypeptide is as follows: MLAGGVRSMPSPLLACWQPILLLVLGSVLSGSATGCPPRCECSAQDRAVLCHRKRFVAVPEGIPTETRL LDLGKNRIKTLNQDEFASFPHLEELELNENIVSAVEPGAFNNLFNLRTLGLRSNRLKLIPLGVFTGLSN LTKLDISENKIVILLDYMFQDLYNLKSLEVGDNDLVYISHRAFSGLNSLEQLTLEKCNLTSIPTEALSH LHGLIVLRLRHLNINAIRDYSFKRLYRLKVLEISHWPYLDTMTPNCLYGLNLTSLSITHCNLTAVPYLA VRHLVYLRFLNLSYNPISTIEGSMLHELLRLQEIQLVGGQLAVVEPYAFRGLNYLRVLNVSGNQLTTLE ESVFHSVGNLETLILDSNPLACDCRLLWVFRRRWRLNFNRQQPTCATPEFVQGKEFKDFPDVLLPNYFT CRRARIRDRKAQQVFVDEGHTVQFVCRADGDPPPAILWLSPRKHLVSAKSNGRLTVFPDGTLEVRYAQV QDNGTYLCIAANAGGNDSMPAHLHVRSYSPDWPHQPNKTFAFISNQPGEGEANSTRATVPFPFDIKTLI IATTMGFISFLGVVLFCLVLLFLWSRGKGNTKHNIEIEYVPRKSDAGISSADAPRKFNMKMI (SEQ ID NO:2). . Sp 3 5 ANTIBODIES [01011 In one embodiment, the present invention is directed to Sp35 antibodies, or antigen-binding fragments,, variants, or derivatives thereof. For example, the present invention includes at least the antigen-binding domains of certain monoclonal antibodies, and fragments, variants, and derivatives thereof shown in Tables 3A and 3B. [01021 Table 3A describes the regions of the Sp35 polypeptide that are bound by certain full-length phage library derived antibodies. These antibodies have the same variable regions as the Fab fragments derived from Phage Display Library-1, as indicated in Table 3B (e.g. D05 in Table 3A has the same variable region as Li05 in Table 3B, D06 in Table 3A has the same variable region as Li06 in Table 3B, etc.). The antibodies were tested for binding Sp 3 5 fragments as defined in Table 3A, using methods well known in the art. [01031 Table 3B describes the ability of the named monoclonal antibodies or Fab fragments to detect Sp35 in various assays such as: Fluorescent Activated Cell Sorting (FACS), Immunoprecipitation (IP), Western blot analysis, Immunohistochemistry (IHC) and Enzyme Linked Immunosorbent Assay (ELISA). Detailed protocols for performing these assays are described herein or are well known and -23 understood by those of ordinary skill in the art. Hybridoma-derived monoclonal antibodies listed in Table 3B were produced by injection of soluble Sp35 into mice and then isolated using hybridoma technology which is well known in the art and described herein. Monoclonal antibodies and antibody Fab fragments listed in Table 3B were isolated from two different phage display libraries using techniques known in the art. TABLE 3A Sp35 D03 D05 D06 DOS D11 D13 D33 Fragment (Li03 (Li05 (Li06 (Li08 (Li03 (Li13 (Li33 Variable Variable Variable Variable Variable Variable Variable Region) Region) Region) Region) Region) Region) Region) 1-432 rat + + + - + -+ 417-493 - +/- +/ - rat Fe AP-Sp35 N/D + -/+ -/+ N/D N/D N/D (1-419) AP-Sp35 N/D - - - N/D N/D N/D (418-498) 417498 - human Fe 417-503 - human Fe 363-498 - human Fe 244-498 - - human Fe C4) 8 a o- 8 o 0 000 0 0 ~~ 9 4C44C 0 4) zo ZZ zoZ, e I) :N (O 0- 0 7 c. 4) cl9 9 a 64) , o r en e nm14mI n e I enl 00 00I r.' r. (ON~'..'0 ~ )0 Ccq3 "i en C11 so06 W 99 u ?s 02 CA ~ ~ 0 0 0 ) V 0 V 0 0 n ,/I Ni4C 4fl %n Lc, 13 ck tn. ON i3 9 0 0 U lo o 0 o 0 tn ci ~. ~ ~ e~0In kT t -Mlw o %0% ae. mr 4:0 41+3 40t n mf, enm " n 27 - O\ 4 r- '4>, >~. tn o %0000 0n as C, - o 088= enenm) -28 [01041 As used herein, the term "antigen binding domain" includes a site that specifically binds an epitope on an antigen (e.g., an epitope of Sp35). The antigen binding domain of an antibody typically includes at least a portion of an immunoglobulin heavy chain variable region and at least a portion of an immunoglobulin light chain variable region. The binding site formed by these variable regions determines the specificity of the antibody. [0105] The present invention is more specifically directed to an Sp35 antibody, or antigen-binding fragment, variant or derivatives thereof, where the Sp35 antibody binds to the same epitope as a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3PID10.2C3, 3P1Eli.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (Li02), 35-E04 (Li03), 36-C09 (LiO4), 30-All (Li05), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (Li08), 36-A12 (Li09), 28-D02 (Lil0), 30-BOl (Li 1l), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lia.2), 3563 (Lla.3), 3564 (Lia.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13). [01061 The invention is further drawn to an Sp35 antibody, or antigen-binding fragment, variant or derivatives thereof, where the Sp35 antibody competitively inhibits a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3P1D1O.2C3, 3P1E1L.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30 C12 (LiOl), 38-DO1 (Li02), 35-E04 (Li03), 36-C09 (LiO4), 30-All (Li05), 34-F02 (Li06), 29-E07 (Li07), 34-G04 (LiO8), 36-A12 (Li09), 28-D02 (LilO), 30-BO1 (Lil l), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13) from binding to Sp35. [01071 The invention is also drawn to an Sp35 antibody, or antigen-binding fragment, variant or derivatives thereof, where the Sp35 antibody comprises at least the antigen binding region of a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3P1D10.2C3, 3PlE1 1.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (Li02), 35-E04 (Li03), 36-C09 (LiO4), 30-All (Li05), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (Li08), 36-A12 (Li09), 28-D02 (LilO), 30-BO1 (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13).

-29 [0108] In certain embodiments, the present invention is directed to an antibody, or antigen-binding fragment, variant, or derivative thereof which specifically or preferentially binds to a particular Sp35 polypeptide fragment or domain. Such Sp35 polypeptide fragments include, but are not limited to, an Sp35 polypeptide comprising, consisting essentially of, or consisting of amino acids 34 to 532; 34 to 417; 34 to 425; 34 to 493; 66 to 532; 66 to 417; 66 to 426; 66 to 493;66 to 532;417 to 532; 417 to 425 (the Sp35 basic region) ; 417 to 493; 417 to 532;, 419 to 493 (the Sp 3 5 Ig region) ;, or 425 to 532 of SEQ ID NO:2; or an Sp35 variant polypeptide at least 70%, 75%, 80%, 85%, 90%, or 95% identical to amino acids 34 to 532; 34 to 417; 34 to 425; 34 to 493; 66 to 532; 66 to 417; 66 to 426; 66 to 493; 66 to 532; 417 to 532; 417 to 425 (the Sp35 basic region) ; 417 to 493; 417 to 532; 419 to 493 (the Sp35 Ig region); or 425 to 532 of SEQ ID NO:2. [01091 Additional Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, but are not limited to those fragments comprising, consisting essentially of, or consisting of one or more leucine-rich-repeats (LRR) of Sp35. Such fragments, include, for example, fragments comprising, consisting essentially of, or consisting of amino acids 66 to 89; 66 to 113; 66 to 137; 90 to 113; 114 to 137; 138 to 161; 162 to 185; 186 to 209; 210 to 233;, 234 to 257; 258 to 281; 282 to 305; 306 to 329; or 330 to 353 of SEQ ID NO:2. Corresponding fragments of a variant Sp 3 5 polypeptide at least 70%, 75%, 80%, 85%, 90%, or 95% identical to amino acids 66 to 89; 66 to 113; 90 to 113; 114 to 137; 138 to 161; 162 to 185; 186 to 209; 210 to 233; 234 to 257; 258 to 281; 282 to 305; 306 to 329; or 330 to 353 of SEQ ID NO:2 are also contemplated. [0110] Additional Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, but are not limited to those fragments comprising, consisting essentially of, or consisting of one or more cysteine rich regions flanking the LRR of Sp35. Such fragments, include, for example, a fragment comprising, consisting essentially of, or consisting of amino acids 34 to 64 of SEQ ID NO:2 (the N-terminal LRR flanking region (LRRNT)), or a fragment comprising, consisting essentially of, or consisting of amino acids 363 to 416 of SEQ ID NO:2 (the C-terminal LRR flanking region (LRRCT)), amino acids Corresponding fragments of a variant Sp35 polypeptide at least 70%, 75%, 80%, 85%, 90%, or 95% identical to amino acids 34 to 64 and 363 to 416 of SEQ ID NO:2 are also contemplated. [01111 As known in the art, "sequence identity" between two polypeptides is determined by comparing the amino acid sequence of one polypeptide to the sequence of a second polypeptide. When discussed herein, whether any particular polypeptide is at least about 70%, 75%, 80%, 85%, 90% or 95% identical to another polypeptide can be determined using methods and computer programs/software known in the art such as, but not limited to, the BESTFIT program (Wisconsin Sequence Analysis Package, Version 8 for Unix, Genetics Computer Group, University Research Park, -30 575 Science Drive, Madison, WI 53711). BESTFIT uses the local homology algorithm of Smith and Waterman, Advances in Applied Mathematics 2:482-489 (1981), to find the best segment of homology between two sequences. When using BESTFIT or any other sequence alignment program to determine whether a particular sequence is, for example, 95% identical to a reference sequence according to the present invention, the parameters are set, of course, such that the percentage of identity is calculated over the full length of the reference polypeptide sequence and that gaps in homology of up to 5% of the total number of amino acids in the reference sequence are allowed. [01121 Additional Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, but are not limited to those fragments comprising, consisting essentially of, or consisting of amino acids 41 to 525 of SEQ ID NO:2; 40 to 526 of SEQ ID NO:2; 39 to 527 of SEQ ID NO:2; 38 to 528 of SEQ ID NO:2; 37 to 529 of SEQ ID NO:2; 36 to 530 of SEQ ID NO:2; 35 to 531 of SEQ ID NO:2; 34 to 531 of SEQ ID NO:2; 46 to 520 of SEQ ID NO:2; 45 to 521 of SEQ ID NO:2; 44 to 522 of SEQ ID NO:2; 43 to 523 of SEQ ID NO:2; and 42 to 524 of SEQ ID NO:2. {01131 Still additional Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, but are not limited to those fragments comprising, consisting essentially of, or consisting of amino acids 1 to 33 of SEQ ID NO:2; I to 35 of SEQ ID NO:2; 34 to 64 of SEQ ID NO:2; 36 to 64 of SEQ ID NO:2; 66 to 89 of SEQ ID NO:2; 90 to 113 of SEQ ID NO:2; 114 to 137 of SEQ ID NO:2; 138 to 161 of SEQ ID NO:2; 162 to 185 of SEQ ID NO:2; 186 to 209 of SEQ ID NO:2; 210 to 233 of SEQ ID NO:2; 234 to 257 of SEQ ID NO:2; 258 to 281 of SEQ ID NO:2; 282 to 305 of SEQ ID NO:2; 306 to 329 of SEQ ID NO:2; 330 to 353 of SEQ ID NO:2; 363 to 416 of SEQ ID NO:2; 417 to 424 of SEQ ID NO:2; 419 to 493 of SEQ ID NO:2; and 494 to 551 of SEQ ID NO:2. [0114] Further still, Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, but are not limited to those fragments comprising, consisting essentially of, or consisting of amino acids 1 to 33 of SEQ ID NO:2; I to 35 of SEQ ID NO:2; I to 64 of SEQ ID NO:2; 1 to 89 of SEQ ID NO:2; 1 to 113 of SEQ ID NO:2; I to 137 of SEQ ID NO:2; I to 161 of SEQ ID NO:2; I to 185 of SEQ ID NO:2; I to 209 of SEQ ID NO:2; 1 to 233 of SEQ ID NO:2; 1 to 257 of SEQ ID NO:2; 1 to 281 of SEQ ID NO:2; 1 to 305 of SEQ ID NO:2; 1 to 329 of SEQ ID NO:2; 1 to 353 of SEQ ID NO:2; 1 to 416 of SEQ ID NO:2; 1 to 424 of SEQ ID NO:2; 1 to 493 of SEQ ID NO:2; 1 to 551 of SEQ ID NO:2; I to 531 of SEQ ID NO:2 and I to 532 of SEQ ID NO:2. [0115] Additional Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, but are not limited to those fragments comprising, consisting essentially of, or consisting of amino acids 34 to 64 of SEQ ID -31 NO:2; 34 to 89 of SEQ ID NO:2; 34 to 113 of SEQ ID NO:2; 34 to 137 of SEQ ID NO:2; 34 to 161 of SEQ ID NO:2; 34 to 185 of SEQ ID NO:2; 34 to 209 of SEQ ID NO:2; 34 to 233 of SEQ ID NO:2; 34 to 257 of SEQ ID NO:2; 34 to 281 of SEQ ID NO:2; 34 to 305 of SEQ ID NO:2; 34 to 329 of SEQ ID NO:2; 34 to 353 of SEQ ID NO:2; 34 to 416 of SEQ ID NO:2; 34 to 424 of SEQ ID NO:2; 34 to 493 of SEQ ID NO:2; and 34 to 551 of SEQ ID NO:2. [0116] More additional Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, but are not limited to those fragments comprising, consisting essentially of, or consisting of amino acids 34 to 530 of SEQ ID NO:2; 34 to 531 of SEQ ID NO:2; 34 to 532 of SEQ ID NO:2; 34 to 533 of SEQ ID NO:2; 34 to 534 of SEQ ID NO:2; 34 to 535 of SEQ ID NO:2; 34 to 536 of SEQ ID NO:2; 34 to 537 of SEQ ID NO:2; 34 to 538 of SEQ ID NO:2; 34 to 539 of SEQ ID NO:2; 30 to 532 of SEQ ID NO:2; 31 to 532 of SEQ ID NO:2; 32 to 532 of SEQ ID NO:2; 33 to 532 of SEQ ID NO:2; 34 to 532 of SEQ ID NO:2; 35 to 532 of SEQ ID NO:2; 36 to 532 of SEQ ID NO:2; 30 to 531 of SEQ ID NO:2; 31 to 531 of SEQ ID NO:2; 32 to 531 of SEQ ID NO:2; 33 to 531 of SEQ ID NO:2; 34 to 531 of SEQ ID NO:2; 35 to 531 of SEQ ID NO:2; and 36 to 531 of SEQ ID NO:2. [01171 Further still, Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, but are not limited to those fragments comprising, consisting essentially of, or consisting of amino acids 36 to 64 of SEQ ]D NO:2; 36 to 89 of SEQ ID NO:2; 36 to 113 of SEQ ID NO:2; 36 to 137 of SEQ ID NO:2; 36 to 161 of SEQ ID NO:2; 36 to 185 of SEQ ID NO:2; 36 to 209 of SEQ ID NO:2; 36 to 233 of SEQ ID NO:2; 36 to 257 of SEQ ID NO:2; 36 to 281 of SEQ ID NO:2; 36 to 305 of SEQ ID NO:2; 36 to 329 of SEQ ID NO:2; 36 to 353 of SEQ ID NO:2; 36 to 416 of SEQ ID NO:2; 36 to 424 of SEQ ID NO:2; 36 to 493 of SEQ ID NO:2; and 36 to 551 of SEQ ID NO:2. [01181 Additional Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, but are not limited to those fragments comprising, consisting essentially of, or consisting of amino acids 36 to 530 of SEQ ID NO:2; 36 to 531 of SEQ ID NO:2; 36 to 532 of SEQ ID NO:2; 36 to 533 of SEQ ID NO:2; 36 to 534 of SEQ ID NO:2; 36 to 535 of SEQ ID NO:2; 36 to 536 of SEQ ID NO:2; 36 to 537 of SEQ ID NO:2; 36 to 538 of SEQ ID NO:2; and 36 to 539 of SEQ ID NO:2. [0119] More Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, but are not limited to those fragments comprising, consisting essentially of, or consisting of amino acids 417 to 493 of SEQ ID NO:2; 417 to 494 of SEQ ID NO:2; 417 to 495 of SEQ ID NO:2; 417 to 496 of SEQ ID NO:2; 417 to 497 of SEQ ID NO:2; 417 to 498 of SEQ ID NO:2; 417 to 499 of SEQ ID NO:2; 417 to 500 of SEQ ID NO:2; 417 to 492 of SEQ ID NO:2; 417 to 491 of SEQ ID NO:2; 412 to 493 of SEQ ID NO:2; 413 to -32 493 of SEQ ID NO:2; 414 to 493 of SEQ ID NO:2; 415 to 493 of SEQ ID NO:2; 416 to 493 of SEQ ID NO:2; 411 to 493 of SEQ ID NO:2; 410 to 493 of SEQ ID NO:2; 410 to 494 of SEQ ED NO:2; 411 to 494 of SEQ ID NO:2; 412 to 494 of SEQ ID NO:2; 413 to 494 of SEQ ID NO:2; 414 to 494 of SEQ ID NO:2; 415 to 494 of SEQ ID NO:2; 416 to 494 of SEQ ID NO:2; 417 to 494 of SEQ ID NO:2; and 418 to 494 of SEQ ID NO:2. [01201 In an additional embodiment Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, an Sp35 polypeptide comprising, consisting essentially of, or consisting of peptides of the Ig domain of Sp35 or fragments, variants, or derivatives of such polypeptides. Specifically, polypeptides comprising, consisting essentially of, or consisting of the following polypeptide sequences: ITX 1

X

2

X

3 (SEQ ID NO:287), ACX 1

X

2

X

3 (SEQ ID NO:288), VCXIX 2

X

3 (SEQ ID NO:289) and SPXIX 2 X3(SEQ ID NO:290) where X, is lysine, arginine, histidine, glutamine, or asparagine, X 2 is lysine, arginine, histidine, glutamine, or asparagine and X 3 is lysine, arginine, histidine, glutamine, or asparagine. For example, Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, those fragments comprising, consisting essentially of, or consisting of the following polypeptide sequences: SPRKH (SEQ ID NO:291), SPRKK (SEQ ID NO:292), SPRKR (SEQ ID NO:293), SPKKH (SEQ ID NO:294), SPHKH (SEQ ID NO:295), SPRRH (SEQ ID NO:296), SPRHH (SEQ ID NO:297), SPRRR (SEQ ID NO:298), SPHHH (SEQ ID NO:299) SPKKK (SEQ ID NO:300), LSPRKH (SEQ ID NO:301), LSPRKK (SEQ ID NO:302), LSPRKR (SEQ ID NO:303), LSPKKH (SEQ ID NO:304), LSPHIKH (SEQ ID NO:305), LSPRRH (SEQ ID NO:306), LSPRHH (SEQ ID NO:307), LSPRRR (SEQ ID NO:308), LSPHIH (SEQ ID NO:309) LSPKKK (SEQ ID NO:310), WLSPRKH (SEQ ID NO:3 11), WLSPRKK (SEQ ID NO:312), WLSPRKR (SEQ ID NO:313), WLSPKKH (SEQ ID NO:314), WLSPHKH (SEQ ID NO:315), WLSPRRH (SEQ ID NO:316), WLSPRHH (SEQ ID NO:317), WLSPRRR (SEQ ID NO:318), WLSPHHH (SEQ ID NO:319) WLSPKKK (SEQ ID NO:320),. These Sp35 polypeptides include the basic "RKH loop" (Arginine-Lysine-Histidine amino acids 456-458) in the Ig domain of Sp 3 5. Additional Sp35 peptides which include a basic tripeptide are ITPKRR (SEQ ID NO:321), ACHHK (SEQ ID NO:322) and VCHHK (SEQ ID NO:323). [0121] Additional Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, an Sp35 polypeptide comprising, consisting essentially of, or consisting of peptides of the Ig domain of Sp35 or fragments, variants, or derivatives of such polypeptides. Specifically, peptides comprising, consisting essentially of, or consisting of the following polypeptide sequences: X4XsRKH (SEQ ID NO:324), X 4

X

5 RRR (SEQ ID NO:325), X4XsKKK (SEQ ID NO:326), X 4

X

5 HHH (SEQ ID NO:327), X 4 XsRKK (SEQ ID NO:328), X 4 XsRKR (SEQ ID NO:329), X 4 XsKKH (SEQ ID NO:330), X 4

X

5 HKH (SEQ ID NO:331), - 33 X 4

X

5 RRH (SEQ ID NO:332) and X 4 XsRHH (SEQ ID NO:333) where X 4 is any amino acid and X 5 is any amino acid. [01221 In other embodiments Sp35 peptide fragments to which certain antibodies, or antigen binding fragments, variants, or derivatives thereof of the present invention bind include, an Sp35 polypeptide comprising, consisting essentially of, or consisting of peptides of the Ig domain of Sp35 or fragments, variants, or derivatives of such polypeptides. Specifically, polypeptides comprising, consisting essentially of, or consisting of the following polypeptide sequences: ITX&X 7

X

8 (SEQ ID NO:334), ACXrX 7 Xs (SEQ ID NO:335), VCX 6

X

7

X

8 (SEQ ID NO:336) and SPX 6

X

7

X

8 (SEQ ID NO:337) where X 6 is lysine, arginine, histidine, glutamine, or asparagine, X 7 is any amino acid and Xg is lysine, arginine, histidine, glutamine, or asparagine. For example, a polypeptide comprising, consisting essentially of, or consisting of the following polypeptide sequence: SPRLH (SEQ ID NO:338). [0123] Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, an Sp35 polypeptide comprising, consisting essentially of, or consisting of peptides which contain amino acids 452-458 in the Ig domain of Sp35,or derivatives thereof, wherein amino acid 452 is a tryptophan or phenylalanine residue. [01241 Additional Sp35 peptide fragments to which certain antibodies, or antigen-binding fragments, variants, or derivatives thereof of the present invention bind include, an Sp35 polypeptide comprising, consisting essentially of, or consisting of peptides of the basic domain of Sp35. Specifically, peptides comprising, consisting essentially of, or consisting of the following polypeptide sequences: RRARIRDRK (SEQ ID NO:339), KKVKVKEKR (SEQ ID NO:340), RRLRLRDRK (SEQ ID NO:341), RRGRGRDRK (SEQ ID NO:342) and RRIRARDRK (SEQ ID NO:343). [01251 Additional exemplary soluble Sp35 polypeptides and methods and materials for obtaining these molecules for producing antibodies or antibody fragments of the present invention may be found, e.g., in International Patent Application No. PCT/US2004/008323, incorporated herein by reference in its entirety. [01261 Methods of making antibodies are well known in the art and described herein. Once antibodies to various fragments of, or to the full-length Sp35 without the signal sequence, have been produced, determining which amino acids, or epitope, of Sp35 to which the antibody or antigen binding fragment binds can be determined by eptiope mapping protocols as described herein as well as methods known in the art (e.g. double antibody-sandwich ELISA as described in "Chapter 11 - Immunology," Current Protocols in Molecular Biology, Ed. Ausubel et al., v.2, John Wiley & Sons, Inc. (1996)). Additional eiptope mapping protocols may be found in Morris, G. Epitope Mapping Protocols, New Jersey: Humana Press (1996), which are both incorporated herein by reference in their entireties.

-34 Epitope mapping can also be performed by commercially available means (i.e. ProtoPROBE, Inc. (Milwaukee, Wisconsin)). [01271 Additionally, antibodies produced which bind to any portion of Sp 3 5 can then be screened for their ability to act as an antagonist of Sp35 and thus promote neurite outgrowth, neuronal and oligodendrocyte survival, proliferation and differentiation as well as promote myelination. Antibodies can be screened for oligodendrocyte/neuronal survival by using the method as described in Examples 10 and 11. Additionally, antibodies can be screened for their ability to promote myelination by using the method of Example 9. Finally, antibodies can be screened for their ability to promote oligodendrocyte proliferation and differentiation, as well as neurite outgrowth by using the method as described in Example 7. Other antagonist functions of antibodies of the present invention can be tested using other assays as described in the Examples herein. [01281 In other embodiments, the present invention includes an antibody, or antigen-binding fragment, variant, or derivative thereof which specifically or preferentially binds to at least one epitope of Sp35, where the epitope comprises, consists essentially of, or consists of at least about four to five amino acids of SEQ ID NO:2, at least seven, at least nine, or between at least about 15 to about 30 amino acids of SEQ ID NO:2. The amino acids of a given epitope of SEQ ID NO:2 as described may be, but need not be contiguous or linear. In certain embodiments, the at least one epitope of Sp35 comprises, consists essentially of, or consists of a non-linear epitope formed by the extracellular domain of Sp35 as expressed on the surface of a cell or as a soluble fragment, e.g., fused to an IgG Fc region. Thus, in certain embodiments the at least one epitope of Sp35 comprises, consists essentially of, or consists of at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 15, at least 20, at least 25, between about 15 to about 30, or at least 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 contiguous or non-contiguous amino acids of SEQ ID NO:2, where the non-contiguous amino acids form an epitope through protein folding. [0129] In other embodiments, the present invention includes an antibody, or antigen-binding fragment, variant, or derivative thereof which specifically or preferentially binds to at least one epitope of Sp35, where the epitope comprises, consists essentially of, or consists of, in addition to one, two, three, four, five, six or more contiguous or non-contiguous amino acids of SEQ ID NO:2 as described above, and an additional moiety which modifies the protein, e.g., a carbohydrate moiety may be included such that the Sp35 antibody binds with higher affinity to modified target protein than it does to an unmodified version of the protein. Alternatively, the Sp35 antibody does not bind the unmodified version of the target protein at all. 101301 In certain aspects, the present invention is directed to an antibody, or antigen-binding fragment, variant, or derivative thereof which specifically binds to a Sp35 polypeptide or fragment - 35 thereof, or an Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) which is less than the KD for said reference monoclonal antibody. [01311 In certain embodiments, an antibody, or antigen-binding fragment, variant, or derivative thereof of the invention binds specifically to at least one epitope of Sp35 or fragment or variant described above, i.e., binds to such an epitope more readily than it would bind to an unrelated, or random epitope; binds preferentially to at least one epitope of Sp35 or fragment or variant described above, i.e., binds to such an epitope more readily than it would bind to a related, similar, homologous, or analogous epitope; competitively inhibits binding of a reference antibody which itself binds specifically or preferentially to a certain epitope of Sp35 or fragment or variant described above; or binds to at least one epitope of Sp35 or fragment or variant described above with an affinity characterized by a dissociation constant KD of less than about 5 x 1 02 M, about 10-2 M, about 5 x 10 M, about 10- M, about 5 x 10-4 M, about 10 ~4 M, about 5 x 10-5 M, about 10~5 M, about 5 x 10-6 M, about 10~ 6 M, about 5 x 10-7 M, about 107 M, about 5 x 108 M, about 10~ M, about 5 x 10- M, about 10-9 M, about 5 x 10-10 M, about 1010 M, about 5 x 10~" M, about 10-11 M, about 5 x 1012 M, about 1012 M, about 5 x 10-13 M, about 10-13 M, about 5 x 10~14 M, about 10-14 M, about 5 x 10-'5 M, or about 10-5 M. In a particular aspect, the antibody or fragment thereof preferentially binds to a human Sp35 polypeptide or fragment thereof, relative to a murine Sp35 polypeptide or fragment thereof. [01321 As used in the context of antibody binding dissociation constants, the term "about" allows for the degree of variation inherent in the methods utilized for measuring antibody affinity. For example, depending on the level of precision of the instrumentation used, standard error based on the number of samples measured, and rounding error, the term "about 102 M" might include, for example, from 0.05 M to 0.005 M. [01331 In specific embodiments, an antibody, or antigen-binding fragment, variant, or derivative thereof of the invention binds Sp35 polypeptides or fragments or variants thereof with an off rate (k(off)) of less than or equal to 5 X 10 sec, 10- sec, 5 X 10-3 sec' or 104 sec-. Alternatively, an antibody, or antigen-binding fragment, variant, or derivative thereof of the invention binds binds Sp35 polypeptides or fragments or variants thereof with an off rate (k(off)) of less than or equal to 5 X 10-4 sec-, 10~4 sec', 5 X 10- 5 sec, or 10~ 5 sec- 5 X 10- 6 sec', 10~ 6 sec', 5 X 10- sec' or 10- 7 sec'. [0134] In other embodiments, an antibody, or antigen-binding fragment, variant, or derivative thereof of the invention binds Sp35 polypeptides or fragments or variants thereof with an on rate (k(on)) of greater than or equal to 103 M 1 sec-1, 5 X 103 M4 sec', 104 M4 sec- or 5 X 104 M' sec 1 . Alternatively, an antibody, or antigen-binding fragment, variant, or derivative thereof of the invention binds Sp35 polypeptides or fragments or variants thereof with an on rate (k(on)) greater than or equal to 10 5 M' sec-, 5 X 10 M sec4, 106 M 1 sec-, or 5 X 106 MV sec- or 107 M 1 sec7'.

-36 [01351 In various embodiments, an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof as described herein is an antagonist of Sp35 activity. In certain embodiments, for example, binding of an antagonist Sp35 antibody to Sp35, as expressed on neurons, blocks myelin associated neurite outgrowth inhibition or neuronal cell death. In other embodiments, binding of the Sp35 antibody to Sp35, as expressed on oligodendrocytes, blocks inhibition of oligodendrocyte growth or differentiation, or blocks demyelination or dysmyelination of CNS neurons. [01361 Unless it is specifically noted, as used herein a "fragment thereof" in reference to an antibody refers to an antigen-binding fragment, i.e., a portion of the antibody which specifically binds to the antigen. In one embodiment, an Sp35 antibody, e.g., an antibody of the invention is a bispecific Sp35 antibody, binding polypeptide, or antibody, e.g., a bispecific antibody, minibody, domain deleted antibody, or fusion protein having binding specificity for more than one epitope, e.g., more than one antigen or more than one epitope on the same antigen. In one embodiment, a bispecific Sp35 antibody, binding polypeptide, or antibody has at least one binding domain specific for at least one epitope on a target polypeptide disclosed herein, e.g., Sp35. In another embodiment, a bispecific Sp35 antibody, binding polypeptide, or antibody has at least one binding domain specific for an epitope on a target polypeptide and at least one target binding domain specific for a drug or toxin. In yet another embodiment, a bispecific Sp35 antibody, binding polypeptide, or antibody has at least one binding domain specific for an epitope on a target polypeptide disclosed herein, and at least one binding domain specific for a prodrug. A bispecific Sp35 antibody, binding polypeptide, or antibody may be a tetravalent antibody that has two target binding domains specific for an epitope of a target polypeptide disclosed herein and two target binding domains specific for a second target. Thus, a tetravalent bispecific Sp35 antibody, binding polypeptide, or antibody may be bivalent for each specificity. [0137] Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention, as known by those of ordinary skill in the art, can comprise a constant region which mediates one or more effector functions. For example, binding of the C1 component of complement to an antibody constant region may activate the complement system. Activation of complement is important in the opsonisation and lysis of cell pathogens. The activation of complement also stimulates the inflammatory response and may also be involved in autoimmune hypersensitivity. Further, antibodies bind to receptors on various cells via the Fc region, with a Fc receptor binding site on the antibody Fc region binding to a Fc receptor (FcR) on a cell. There are a number of Fc receptors which are specific for different classes of antibody, including IgG (gamma receptors), IgE (epsilon receptors), IgA (alpha receptors) and IgM (mu receptors). Binding of antibody to Fc receptors on cell surfaces triggers a number of important and diverse biological responses including engulfnent and destruction of antibody-coated particles, clearance of immune complexes, lysis of antibody-coated target cells by -37 killer cells (called antibody-dependent cell-mediated cytotoxicity, or ADCC), release of inflammatory mediators, placental transfer and control of immunoglobulin production. [0138] Accordingly, certain embodiments of the invention include an Sp35 antibody, or antigen binding fragment, variant, or derivative thereof, in which at least a fraction of one or more of the constant region domains has been deleted or otherwise altered so as to provide desired biochemical characteristics such as reduced effector functions, the ability to non-covalently dimerize, increased ability to localize at the site of a tumor, reduced serum half-life, or increased serum half-life when compared with a whole, unaltered antibody of approximately the same immunogenicity. For example, certain antibodies for use in the diagnostic and treatment methods described herein are domain deleted antibodies which comprise a polypeptide chain similar to an immunoglobulin heavy chain, but which lack at least a portion of one or more heavy chain domains. For instance, in certain antibodies, one entire domain of the constant region of the modified antibody will be deleted, for example, all or part of the CH 2 domain will be deleted. [0139] In certain Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof described herein, the Fe portion may be mutated to decrease effector function using techniques known in the art. For example, the deletion or inactivation (through point mutations or other means) of a constant region domain may reduce Fc receptor binding of the circulating modified antibody thereby increasing tumor localization. In other cases it may be that constant region modifications consistent with the instant invention moderate complement binding and thus reduce the serum half life and nonspecific association of a conjugated cytotoxin. Yet other modifications of the constant region may be used to modify disulfide linkages or oligosaccharide moieties that allow for enhanced localization due to increased antigen specificity or antibody flexibility. The resulting physiological, profile, bioavailability and other biochemical effects of the modifications, such as tumor localization, biodistribution and serum half-life, may easily be measured and quantified using well know immunological techniques without undue experimentation. [01401 Modified forms of Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be made from whole precursor or parent antibodies using techniques known in the art. Exemplary techniques are discussed in more detail herein. [01411 In certain embodiments both the variable and constant regions of Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof are fully human. Fully human antibodies can be made using techniques that are known in the art and as described herein. For example, fully human antibodies against a specific antigen can be prepared by administering the antigen to a transgenic animal which has been modified to produce such antibodies in response to antigenic challenge, but whose endogenous loci have been disabled. Exemplary techniques that can be used to make such antibodies are described in US patents: 6,150,584; 6,458,592; 6,420,140 which are -38 incorporated by reference in their entireties. Other techniques are known in the art. Fully human antibodies can likewise be produced by various display technologies, e.g., phage display or other viral display systems, as described in more detail elsewhere herein. [01421 Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be made or manufactured using techniques that are known in the art. In certain embodiments, antibody molecules or fragments thereof are "recombinantly produced," i.e., are produced using recombinant DNA technology. Exemplary techniques for making antibody molecules or fragments thereof are discussed in more detail elsewhere herein. [01431 Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention also include derivatives that are modified, e.g., by the covalent attachment of any type of molecule to the antibody such that covalent attachment does not prevent the antibody from specifically binding to its cognate epitope. For example, but not by way of limitation, the antibody derivatives include antibodies that have been modified, e.g., by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. Any of numerous chemical modifications may be carried out by known techniques, including, but not limited to specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Additionally, the derivative may contain one or more non-classical amino acids. [0144] In certain embodiments, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention will not elicit a deleterious immune response in the animal to be treated, e.g., in a human. In one embodiment,. Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention are modified to reduce their immunogenicity using art recognized techniques. For example, antibodies can be humanized, primatized, deimmunized, or chimeric antibodies can be made. These types of antibodies are derived from a non-human antibody, typically a murine or primate antibody, that retains or substantially retains the antigen-binding properties of the parent antibody, but which is less immunogenic in humans. This may be achieved by various methods, including (a) grafting the entire non-human variable domains onto human constant regions to generate chimeric antibodies; (b) grafting at least a part of one or more of the non-human complementarity determining regions (CDRs) into a human framework and constant regions with or without retention of critical framework residues; or (c) transplanting the entire non-human variable domains, but "cloaking" them with a human-like section by replacement of surface residues. Such methods are disclosed in Morrison et al., Proc. Natl. Acad. Sci. 81:6851-6855 (1984); Morrison et al., Adv. Immunol. 44:65-92 (1988); Verhoeyen et al., Science 239:1534-1536 (1988); Padlan, Molec. Immun. 28:489-498 (1991); Padlan, Molec. Immun. 31:169-217 (1994), and U.S. Pat. Nos. 5,585,089, 5,693,761, 5,693,762, and 6,190,370, all of which are hereby incorporated by reference in their entirety.

-39 [01451 De-immunization can also be used to decrease the immunogenicity of an antibody. As used herein, the term "de-immunization" includes alteration of an antibody to modify T cell epitopes (see, e.g., W09852976A1, W00034317A2). For example, VH and VL sequences from the starting antibody are analyzed and a human T cell epitope "map" from each V region showing the location of epitopes in relation to complementarity-determining regions (CDRs) and other key residues within the sequence. Individual T cell epitopes from the T cell epitope map are analyzed in order to identify alternative amino acid substitutions with a low risk of altering activity of the final antibody. A range of alternative VH and VL sequences are designed comprising combinations of amino acid substitutions and these sequences are subsequently incorporated into a range of binding polypeptides, e.g., Sp35-specific antibodies or immunospecific fragments thereof for use in the diagnostic and treatment methods disclosed herein, which are then tested for function. Typically, between 12 and 24 variant antibodies are generated and tested. Complete heavy and light chain genes comprising modified V and human C regions are then cloned into expression vectors and the subsequent plasmids introduced into cell lines for the production of whole antibody. The antibodies are then compared in appropriate biochemical and biological assays, and the optimal variant is identified. [01461 Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention may be generated by any suitable method known in the art. Polyclonal antibodies to an antigen of interest can be produced by various procedures well known in the art. For example, an Sp35 antibody, e.g., a binding polypeptide, e.g., an Sp35-specific antibody or immunospecific fragment thereof can be administered to various host animals including, but not limited to, rabbits, mice, rats, chickens, hamsters, goats, donkeys, etc., to induce the production of sera containing polyclonal antibodies specific for the antigen. Various adjuvants may be used to increase the immunological response, depending on the host species, and include but are not limited to, Freund's (complete and incomplete), mineral gels such as aluminum hydroxide, surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides, oil emulsions, keyhole limpet hemocyanins, dinitrophenol, and potentially useful human adjuvants such as BCG (bacille Calmette-Guerin) and Corynebacterium parvum. Such adjuvants are also well known in the art. [01471 Monoclonal antibodies can be prepared using a wide variety of techniques known in the art including the use of hybridoma, recombinant, and phage display technologies, or a combination thereof. For example, monoclonal antibodies can be produced using hybridoma techniques including those known in the art and taught, for example, in Harlow et al., Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, 2nd ed. (1988); Hammerling et al., in: Monoclonal Antibodies and T Cell Hybridomas Elsevier, N.Y., 563-681 (1981) (said references incorporated by reference in their entireties). The term "monoclonal antibody" as used herein is not limited to antibodies produced through hybridoma technology. The term "monoclonal antibody" refers to an antibody that is derived -40 from a single clone, including any eukaryotic, prokaryotic, or phage clone, and not the method by which it is produced. Thus, the term "monoclonal antibody" is not limited to antibodies produced through hybridoma technology. Monoclonal antibodies can be prepared using Sp35 knockout mice to increase the regions of epitope recognition. Monoclonal antibodies can be prepared using a wide variety of techniques known in the art including the use of hybridoma and recombinant and phage display technology as described elsewhere herein. [01481 Using art recognized protocols, in one example, antibodies are raised in mammals by multiple subcutaneous or intraperitoneal injections of the relevant antigen (e.g., purified tumor associated antigens such as Sp35 or cells or cellular extracts comprising such antigens) and an adjuvant. This immunization typically elicits an immune response that comprises production of antigen-reactive antibodies from activated splenocytes or lymphocytes. While the resulting antibodies may be harvested from the serum of the animal to provide polyclonal preparations, it is often desirable to isolate individual lymphocytes from the spleen, lymph nodes or peripheral blood to provide homogenous preparations of monoclonal antibodies (MAbs). Preferably, the lymphocytes are obtained from the spleen. [01491 In this well known process (Kohler et al., Nature 256:495 (1975)) the relatively short-lived, or mortal, lymphocytes from a mammal which has been injected with antigen are fused with an immortal tumor cell line (e.g. a myeloma cell line), thus, producing hybrid cells or "hybridomas" which are both immortal and capable of producing the genetically coded antibody of the B cell. The resulting hybrids are segregated into single genetic strains by selection, dilution, and regrowth with each individual strain comprising specific genes for the formation of a single antibody. They produce antibodies which are homogeneous against a desired antigen and, in reference to their pure genetic parentage, are termed "monoclonal." [01501 Hybridoma cells thus prepared are seeded and grown in a suitable culture medium that preferably contains one or more substances that inhibit the growth or survival of the unfused, parental myeloma cells. Those skilled in the art will appreciate that reagents, cell lines and media for the formation, selection and growth of hybridomas are commercially available from a number of sources and standardized protocols are well established. Generally, culture medium in which the hybridoma cells are growing is assayed for production of monoclonal antibodies against the desired antigen. Preferably, the binding specificity of the monoclonal antibodies produced by hybridoma cells is determined by in vitro assays such as immunoprecipitation, radioimmunoassay (RIA) or enzyme-linked immunoabsorbent assay (ELISA). After hybridoma cells are identified that produce antibodies of the desired specificity, affinity and/or activity, the clones may be subcloned by limiting dilution procedures and grown by standard methods (Goding, Monoclonal Antibodies: Principles and Practice, Academic Press, pp 59-103 (1986)). It will further be appreciated that the monoclonal antibodies secreted by the -41 subclones may be separated from culture medium, ascites fluid or serum by conventional purification procedures such as, for example, protein-A, hydroxylapatite chromatography, gel electrophoresis, dialysis or affinity chromatography. [0151] Antibody fragments that recognize specific epitopes may be generated by known techniques. For example, Fab and F(ab') 2 fragments may be produced by proteolytic cleavage of immunoglobulin molecules, using enzymes such as papain (to produce Fab fragments) or pepsin (to produce F(ab) 2 fragments). F(ab)2 fragments contain the variable region, the light chain constant region and the CH1 domain of the heavy chain. [01521 Those skilled in the art will also appreciate that DNA encoding antibodies or antibody fragments (e.g., antigen binding sites) may also be derived from antibody libraries, such as phage display libraries. In a particular, such phage can be utilized to display antigen-binding domains expressed from a repertoire or combinatorial antibody library (e.g., human or murine). Phage expressing an antigen binding domain that binds the antigen of interest can be selected or identified with antigen, e.g., using labeled antigen or antigen bound or captured to a solid surface or bead. Phage used in these methods are typically filamentous phage including fd and M13 binding domains expressed from phage with Fab, Fv OE DAB (individiual Fv region from light or heavy chains)or disulfide stabilized Fv antibody domains recombinantly fused to either the phage gene III or gene VIII protein. Exemplary methods are set forth, for example, in EP 368 684 B1; U.S. patent. 5,969,108, Hoogenboom, H.R. and Chames, Immunol. Today 21:371 (2000); Nagy et al. Nat. Med. 8:801 (2002); Huie et al., Proc. Nat!. Acad. Sci. USA 98:2682 (2001); Lui et al., J. Mol. Biol. 315:1063 (2002), each of which is incorporated herein by reference. Several publications (e.g., Marks et al., BiolTechnology 10:779-783 (1992)) have described the production of high affinity human antibodies by chain shuffling, as well as combinatorial infection and in vivo recombination as a strategy for constructing large phage libraries. In another embodiment, Ribosomal display can be used to replace bacteriophage as the display platform (see, e.g., Hanes et al., Nat. Biotechnol. 18:1287 (2000); Wilson et al., Proc. Nat. Acad. Sci. USA 98:3750 (2001); or Irving et al., J. Immunol. Methods 248:31 (2001)). In yet another embodiment, cell surface libraries can be screened for antibodies (Boder et al., Proc. Nat!. Acad. Sci. USA 97:10701 (2000); Daugherty et al., J. Immunol. Methods 243:211 (2000)). Such procedures provide alternatives to traditional hybridoma techniques for the isolation and subsequent cloning of monoclonal antibodies. [0153] In phage display methods, functional antibody domains are displayed on the surface of phage particles which carry the polynucleotide sequences encoding them. For example, DNA sequences encoding VH and VL regions are amplified from animal cDNA libraries (e.g., human or murine cDNA libraries of lymphoid tissues) or synthetic cDNA libraries. In certain embodiments, the DNA encoding the VH and VL regions are joined together by an scFv linker by PCR and cloned into a -42 phagemid vector (e.g., p CANTAB 6 or pComb 3 HSS). The vector is electroporated in E. coli and the E. coli is infected with helper phage. Phage used in these methods are typically filamentous phage including fd and M13 and the VH or VL regions are usually recombinantly fused to either the phage gene III or gene VII. Phage expressing an antigen binding domain that binds to an antigen of interest (i.e., an Sp35 polypeptide or a fragment thereof) can be selected or identified with antigen, e.g., using labeled antigen or antigen bound or captured to a solid surface or bead. [0154] Additional examples of phage display methods that can be used to make the antibodies include those disclosed in Brinkman et al., J. Immunol. Methods 182:41-50 (1995); Ames et al., J. Immunol. Methods 184:177-186 (1995); Kettleborough et al., Eur. J. Immunol. 24:952-958 (1994); Persic et al., Gene 187:9-18 (1997); Burton et al., Advances in Immunology 57:191-280 (1994); PCT Application No. PCT/GB91/01134; PCT publications WO 90/02809; WO 91/10737; WO 92/01047; WO 92/18619; WO 93/11236; WO 95/15982; WO 95/20401; and U.S. Pat. Nos. 5,698,426; 5,223,409; 5,403,484; 5,580,717; 5,427,908; 5,750,753; 5,821,047; 5,571,698; 5,427,908; 5,516,637; 5,780,225; 5,658,727; 5,733,743 and 5,969,108; each of which is incorporated herein by reference in its entirety. [0155] As described in the above references, after phage selection, the antibody coding regions from the phage can be isolated and used to generate whole antibodies, including human antibodies, or any other desired antigen binding fragment, and expressed in any desired host, including mammalian cells, insect cells, plant cells, yeast, and bacteria. For example, techniques to recombinantly produce Fab, Fab' and F(ab') 2 fragments can also be employed using methods known in the art such as those disclosed in PCT publication WO 92/22324; Mullinax et al., BioTechniques 12(6):864-869 (1992); and Sawai et al., AJRI 34:26-34 (1995); and Better et al., Science 240:1041-1043 (1988) (said references incorporated by reference in their entireties). [01561 Examples of techniques which can be used to produce single-chain Fvs and antibodies include those described in U.S. Pat. Nos. 4,946,778 and 5,258,498; Huston et al., Methods in Enzymology 203:46-88 (1991); Shu et al., PNAS 90:7995-7999 (1993); and Skerra et al., Science 240:1038-1040 (1988). For some uses, including in vivo use of antibodies in humans and in vitro detection assays, it may be preferable to use chimeric, humanized, or human antibodies. A chimeric antibody is a molecule in which different portions of the antibody are derived from different animal species, such as antibodies having a variable region derived from a murine monoclonal antibody and a human immunoglobulin constant region. Methods for producing chimeric antibodies are known in the art. See, e.g., Morrison, Science 229:1202 (1985); Oi et al., BioTechniques 4:214 (1986); Gillies et al., J. Immunol. Methods 125:191-202 (1989); U.S. Pat. Nos. 5,807,715; 4,816,567; and 4,816397, which are incorporated herein by reference in their entireties. Humanized antibodies are antibody molecules derived from a non-human species antibody that bind the desired antigen having one or more complementarity determining regions (CDRs) from the non-human species and framework regions -43 from a human immunoglobulin molecule. Often, framework residues in the human framework regions will be substituted with the corresponding residue from the CDR donor antibody to alter, preferably improve, antigen binding. These framework substitutions are identified by methods well known in the art, e.g., by modeling of the interactions of the CDR and framework residues to identify framework residues important for antigen binding and sequence comparison to identify unusual framework residues at particular positions. (See, e.g., Queen et al., U.S. Pat. No. 5,585,089; Riechmann et al., Nature 332:323 (1988), which are incorporated herein by reference in their entireties.) Antibodies can be humanized using a variety of techniques known in the art including, for example, CDR-grafting (EP 239,400; PCT publication WO 91/09967; U.S. Pat. Nos. 5,225,539; 5,530,101; and 5,585,089), veneering or resurfacing (EP 592,106; EP 519,596; Padlan, Molecular Immunology 28(4/5):489-498 (1991); Studnicka et al., Protein Engineering 7(6):805-814 (1994); Roguska. et al., PNAS 91:969-973 (1994)), and chain shuffling (U.S. Pat. No. 5,565,332, which is incorporated by reference in its entirety). [01571 Completely human antibodies are particularly desirable for therapeutic treatment of human patients. Human antibodies can be made by a variety of methods known in the art including phage display methods described above using antibody libraries derived from human immunoglobulin sequences. See also, U.S. Pat. Nos. 4,444,887 and 4,716,111; and PCT publications WO 98/46645, WO 98/50433, WO 98/24893, WO 98/16654, WO 96/34096, WO 96/33735, and WO 91/10741; each of which is incorporated herein by reference in its entirety. [0158] Human antibodies can also be produced using transgenic mice which are incapable of expressing functional endogenous immunoglobulins, but which can express human immunoglobulin genes. For example, the human heavy and light chain immunoglobulin gene complexes may be introduced randomly or by homologous recombination into mouse embryonic stem cells. Alternatively, the human variable region, constant region, and diversity region may be introduced into mouse embryonic stem cells in addition to the human heavy and light chain genes. The mouse heavy and light chain immunoglobulin genes may be rendered non-functional separately or simultaneously with the introduction of human immunoglobulin loci by homologous recombination. In particular, homozygous deletion of the JH region prevents endogenous antibody production. The modified embryonic stem cells are expanded and microinjected into blastocysts to produce chimeric mice. The chimeric mice are then bred to produce homozygous offspring that express human antibodies. The transgenic mice are immunized in the normal fashion with a selected antigen, e.g., all or a portion of a desired target polypeptide. Monoclonal antibodies directed against the antigen can be obtained from the immunized, transgenic mice using conventional hybridoma technology. The human immunoglobulin transgenes harbored by the transgenic mice rearrange during B-cell differentiation, and subsequently undergo class switching and somatic mutation. Thus, using such a technique, it is possible to produce therapeutically -44 useful IgG, IgA, IgM and IgE antibodies. For an overview of this technology for producing human antibodies, see Lonberg and Huszar Int. Rev. Immunol. 13:65-93 (1995). For a detailed discussion of this technology for producing human antibodies and human monoclonal antibodies and protocols for producing such antibodies, see, e.g., PCT publications WO 98/24893; WO 96/34096; WO 96/33735; U.S. Pat. Nos. 5,413,923; 5,625,126; 5,633,425; 5,569,825; 5,661,016; 5,545,806; 5,814,318; and 5,939,598, which are incorporated by reference herein in their entirety. In addition, companies such as Abgenix, Inc. (Freemont, Calif.) and GenPharm (San Jose, Calif.) can be engaged to provide human antibodies directed against a selected antigen using technology similar to that described above. [01591 Completely human antibodies which recognize a selected epitope can be generated using a technique referred to as "guided selection." In this approach a selected non-human monoclonal antibody, e.g., a mouse antibody, is used to guide the selection of a completely human antibody recognizing the same epitope. (Jespers et al., Bio/Technology 12:899-903 (1988). See also, U.S. Patent No. 5,565,332, which is incorporated by reference in its entirety.) [01601 Further, antibodies to target polypeptides of the invention can, in turn, be utilized to generate anti-idiotype antibodies that "mimic" target polypeptides using techniques well known to those skilled in the art. (See, e.g., Greenspan & Bona, FASEB J. 7(5):437-444 (1989) and Nissinoff, J. Immunol. 147(8):2429-2438 (1991)). For example, antibodies which bind to and competitively inhibit polypeptide multimerization and/or binding of a polypeptide of the invention to a ligand can be used to generate anti-idiotypes that "mimic" the polypeptide multimerization and/or binding domain and, as a consequence, bind to and neutralize polypeptide and/or its ligand. Such neutralizing anti-idiotypes or Fab fragments of such anti-idiotypes can be used in therapeutic regimens to neutralize polypeptide ligand. For example, such anti-idiotypic antibodies can be used to bind a desired target polypeptide and/or to bind its ligands/receptors, and thereby block its biological activity. [0161] In another embodiment, DNA encoding desired monoclonal antibodies may be readily isolated and sequenced using conventional procedures (e.g., by using oligonucleotide probes that are capable of binding specifically to genes encoding the heavy and light chains of murine antibodies). The isolated and subcloned hybridoma cells serve as a preferred source of such DNA. Once isolated, the DNA may be placed into expression vectors, which are then transfected into prokaryotic or eukaryotic host cells such as E. coli cells, simian COS cells, Chinese Hamster Ovary (CHO) cells or myeloma cells that do not otherwise produce immunoglobulins. More particularly, the isolated DNA (which may be synthetic as described herein) may be used to clone constant and variable region sequences for the manufacture antibodies as described in Newman et al., U.S. Pat. No. 5,658,570, filed January 25, 1995, which is incorporated by reference herein. Essentially, this entails extraction of RNA from the selected cells, conversion to cDNA, and amplification by PCR using Ig specific primers. Suitable primers for this purpose are also described in U.S. Pat. No. 5,658,570. As will be discussed in more detail below, -45 transformed cells expressing the desired antibody may be grown up in relatively large quantities to provide clinical and commercial supplies of the immunoglobulin. [0162] In one embodiment, an Sp35 antibody of the invention comprises at least one heavy or light chain CDR of an antibody molecule. In another embodiment, an Sp35 antibody of the invention comprises at least two CDRs from one or more antibody molecules. In another embodiment, an Sp35 antibody of the invention comprises at least three CDRs from one or more antibody molecules. In another embodiment, an Sp35 antibody of the invention comprises at least four CDRs from one or more antibody molecules. In another embodiment, an Sp35 antibody of the invention comprises at least five CDRs from one or more antibody molecules. In another embodiment, an Sp35 antibody of the invention comprises at least six CDRs from one or more antibody molecules. Exemplary antibody molecules comprising at least one CDR that can be included in the subject Sp35 antibodies are described herein. [01631 In a specific embodiment, the amino acid sequence of the heavy and/or light chain variable domains may be inspected to identify the sequences of the complementarity determining regions (CDRs) by methods that are well know in the art, e.g., by comparison to known amino acid sequences of other heavy and light chain variable regions to determine the regions of sequence hypervariability. Using routine recombinant DNA techniques, one or more of the CDRs may be inserted within framework regions, e.g., into human framework regions to humanize a non-human antibody. The framework regions may be naturally occurring or consensus framework regions, and preferably human framework regions (see, e.g., Chothia et al., J. Mol. Biol. 278:457-479 (1998) for a listing of human framework regions). Preferably, the polynucleotide generated by the combination of the framework regions and CDRs encodes an antibody that specifically binds to at least one epitope of a desired polypeptide, e.g., Sp35. Preferably, one or more amino acid substitutions may be made within the framework regions, and, preferably, the amino acid substitutions improve binding of the antibody to its antigen. Additionally, such methods may be used to make amino acid substitutions or deletions of one or more variable region cysteine residues participating in an intrachain disulfide bond to generate antibody molecules lacking one or more intrachain disulfide bonds. Other alterations to the polynucleotide are encompassed by the present invention and within the skill of the art. [01641 In addition, techniques developed for the production of "chimeric antibodies" (Morrison et al., Proc. Nati. Acad. Sci. 81:851-855 (1984); Neuberger et al., Nature 312:604-608 (1984); Takeda et al., Nature 314:452-454 (1985)) by splicing genes from a mouse antibody molecule of appropriate antigen specificity together with genes from a human antibody molecule of appropriate biological activity can be used. As used herein, a chimeric antibody is a molecule in which different portions are derived from different animal species, such as those having a variable region derived from a murine monoclonal antibody and a human immunoglobulin constant region, e.g., humanized antibodies.

-46 [0165] Alternatively, techniques described for the production of single chain antibodies (U.S. Pat. No. 4,694,778; Bird, Science 242:423-442 (1988); Huston et al., Proc. Natl. Acad. Sci. USA 85:5879 5883 (1988); and Ward et al., Nature 334:544-554 (1989)) can be adapted to produce single chain antibodies. Single chain antibodies are formed by linking the heavy and light chain fragments of the Fv region via an amino acid bridge, resulting in a single chain antibody. Techniques for the assembly of functional Fv fragments in E. coli may also be used (Skerra et al., Science 242:1038-1041 (1988)). [01661 Yet other embodiments of the present invention comprise the generation of human or substantially human antibodies in transgenic animals (e.g., mice) that are incapable of endogenous immunoglobulin production (see e.g., U.S. Pat. Nos. 6,075,181, 5,939,598, 5,591,669 and 5,589,369 each of which is incorporated herein by reference). For example, it has been described that the homozygous deletion of the antibody heavy-chain joining region in chimeric and germ-line mutant mice results in complete inhibition of endogenous antibody production. Transfer of a human .immunoglobulin gene array to such germ line mutant mice will result in the production of human antibodies upon antigen challenge. Another preferred means of generating human antibodies using SCID mice is disclosed in U.S. Pat. No. 5,811,524 which is incorporated herein by reference. It will be appreciated that the genetic material associated with these human antibodies may also be isolated and manipulated as described herein. [0167] Yet another highly efficient means for generating recombinant antibodies is disclosed by Newman, Biotechnology 10: 1455-1460 (1992). Specifically, this technique results in the generation of primatized antibodies that contain monkey variable domains and human constant sequences. This reference is incorporated by reference in its entirety herein. Moreover, this technique is also described in commonly assigned U.S. Pat. Nos. 5,658,570, 5,693,780 and 5,756,096 each of which is incorporated herein by reference. [0168] In another embodiment, lymphocytes can be selected by micromanipulation and the variable genes isolated. For example, peripheral blood mononuclear cells can be isolated from an immunized mammal and cultured for about 7 days in vitro. The cultures can be screened for specific IgGs that meet the screening criteria. Cells from positive wells can be isolated. Individual Ig producing B cells can be isolated by FACS or by identifying them in a complement-mediated hemolytic plaque assay. Ig-producing B cells can be micromanipulated into a tube and the VH and VL genes can be amplified using, e.g., RT-PCR. The VH and VL genes can be cloned into an antibody expression vector and transfected into cells (e.g., eukaryotic or prokaryotic cells) for expression. [01691 Alternatively, antibody-producing cell lines may be selected and cultured using techniques well known to the skilled artisan. Such techniques are described in a variety of laboratory manuals and primary publications. In this respect, techniques suitable for use in the invention as described below are described in Current Protocols in Immunology, Coligan et al., Eds., Green Publishing Associates and -47 Wiley-Interscience, John Wiley and Sons, New York (1991) which is herein incorporated by reference in its entirety, including supplements. [0170] Antibodies for use in the diagnostic and therapeutic methods disclosed herein can be produced by any method known in the art for the synthesis of antibodies, in particular, by chemical synthesis or preferably, by recombinant expression techniques as described herein. [01711 In one embodiment, an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof of the invention comprises a synthetic constant region wherein one or more domains are partially or entirely deleted ("domain-deleted antibodies"). In certain embodiments compatible modified antibodies will comprise domain deleted constructs or variants wherein the entire CH2 domain has been removed (ACH2 constructs). For other embodiments a short connecting peptide may be substituted for the deleted domain to provide flexibility and freedom of movement for the variable region. Those skilled in the art will appreciate that such constructs are particularly preferred due to the regulatory properties of the CH2 domain on the catabolic rate of the antibody. Domain deleted constructs can be derived using a vector (e.g., from Biogen IDEC Incorporated) encoding an IgGi human constant domain (see, e.g., WO 02/060955A2 and W002/096948A2, which are incorporated by reference in their entireties). This exemplary vector was engineered to delete the CH 2 domain and provide a synthetic vector expressing a domain deleted IgG, constant region. [01721 In certain embodiments, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention are minibodies. Minibodies can be made using methods described in the art (see, e.g., see e.g., US patent 5,837,821 or WO 94/09817A1, which are incorporated by reference in their entireties). [0173] In one embodiment, an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof of the invention comprises an immunogIobulin heavy chain having deletion or substitution of a few or even a single amino acid as long as it permits association between the monomeric subunits. For example, the mutation of a single amino acid in selected areas of the CH2 domain may be enough to substantially reduce Fc binding and thereby increase tumor localization. Similarly, it may be desirable to simply delete that part of one or more constant region domains that control the effector function (e.g. complement binding) to be modulated. Such partial deletions of the constant regions may improve selected characteristics of the antibody (serum half-life) while leaving other desirable functions associated with the subject constant region domain intact. Moreover, as alluded to above, the constant regions of the disclosed antibodies may be synthetic through the mutation or substitution of one or more amino acids that enhances the profile of the resulting construct. In this respect it may be possible to disrupt the activity provided by a conserved binding site (e.g. Fc binding) while substantially maintaining the configuration and immunogenic profile of the modified antibody. Yet other embodiments comprise the addition of one or more amino acids to the constant region to enhance -48 desirable characteristics such as effector function or provide for more cytotoxin or carbohydrate attachment. In such embodiments it may be desirable to insert or replicate specific sequences derived from selected constant region domains. [0174] The present invention also provides antibodies that comprise, consist essentially of, or consist of, variants (including derivatives) of antibody molecules (e.g., the VH regions and/or VL regions) described herein, which antibodies or fragments thereof immunospecifically bind to an Sp35 polypeptide or fragment or variant thereof. Standard techniques known to those of skill in the art can be used to introduce mutations in the nucleotide sequence encoding an Sp35 antibody, including, but not limited to, site-directed mutagenesis and PCR-mediated mutagenesis which result in amino acid substitutions. Preferably, the variants (including derivatives) encode less than 50 amino acid substitutions, less than 40 amino acid subsitutions, less than 30 amino acid substitutions, less than 25 amino acid substitutions, less than 20 amino acid substitutions, less than 15 amino acid substitutions, less than 10 amino acid substitutions, less than 5 amino acid substitutions, less than 4 amino acid substitutions, less than 3 amino acid substitutions, or less than 2 amino acid substitutions relative to the reference VH region, VHCDRl, VHCDR2, VHCDR3, VL region, VLCDRl, VLCDR2, or VLCDR3. A "conservative amino acid substitution" is one in which the amino acid residue is replaced with an amino acid residue having a side chain with a similar charge. Families of amino acid residues having side chains with similar charges have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains ( e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Alternatively, mutations can be introduced randomly along all or part of the coding sequence, such as by saturation mutagenesis, and the resultant mutants can be screened for biological activity to identify mutants that retain activity (e.g., the ability to bind an Sp35 polypeptide). [0175] For example, it is possible to introduce mutations only in framework regions or only in CDR regions of an antibody molecule. Introduced mutations may be silent or neutral missense mutations, i.e., have no, or little, effect on an antibody's ability to bind antigen. These types of mutations may be useful to optimize codon usage, or improve a hybridoma's antibody production. Alternatively, non-neutral missense mutations may alter an antibody's ability to bind antigen. The location of most silent and neutral missense mutations is likely to be in the framework regions, while the location of most non-neutral missense mutations is likely to be in CDR, though this is not an absolute requirement. One of skill in the art would be able to design and test mutant molecules with desired properties such as no alteration in antigen binding activity or alteration in binding activity (e.g., -49 improvements in antigen binding activity or change in antibody specificity). Following mutagenesis, the encoded protein may routinely be expressed and the functional and/or biological activity of the encoded protein, (e.g., ability to immunospecifically bind at least one epitope of an Sp35 polypeptide) can be determined using techniques described herein or by routinely modifying techniques known in the art. IV. POLYNUCLEOTIDES ENCODING Sp35 ANTIBODIES [0176] The present invention also provides for nucleic acid molecules encoding Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention. [0177] In one embodiment, the present invention provides an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid encoding an immunoglobulin heavy chain variable region (VH), where at least one of the CDRs of the heavy chain variable region or at least two of the CDRs of the heavy chain variable region are at least 80%, 85%, 90% or 95% identical to reference heavy chain CDR1, CDR2, or CDR3 amino acid sequences from monoclonal Sp35 antibodies disclosed herein. Alternatively, the CDRI, CDR2, and CDR3 regions of the VH are at least 80%, 85%, 90% or 95% identical to reference heavy chain CDR1, CDR2, and CDR3 amino acid sequences from monoclonal Sp35 antibodies disclosed herein. Thus, according to this embodiment a heavy chain variable region of the invention has CDR1, CDR2, or CDR3 polypeptide sequences related to the polypeptide sequences shown in Table 4: TABLE 4: Reference VH CDR1, CDR2, and CDR3 amino acid sequences* Antibody Name VH-CDR1 VH-CDR2 VH-CDR3 P=TYPMV P-WIGPSGOVTAYADSVKG P-=PYSSGWWDFDL (SEQ ID NO:6) (SEQ ID NO:8) (SEQ ID NO:10) Lilo N=ACTTACCCTATGGTT N=TGGATCGGTCCTTCT N-CCCTATAGCAGTGGCT (SEQ ID NO:5) GGTGGCGTTACTGCTTA GGTGGGACTTCGATCTC TGCTGACTCCGTTAAAGGT (SEQ ID NO:9) (SEQ ID NO:7) P=MYFMG P=SISPSGGFTSYADSVKG P-DRHAFDI (SEQ ID NO:12) (SEQ IDNO:14) (SEQ ID NO:16) Li07 N=ATGTACTTTATGGGT N-TCTATCTCTCCTTCTGGTGGCTTTAC N=GATCGGCATGCTTTTGATATC (SEQ ID NO: 11) TTCTTATGCTGACTCCGTTAAAGGT (SEQ ID NO:15) (SEQ ID NO:13) P=AYAMG P=SIVSSGGYTDYADSVKG P=EGDHNAFDI (SEQ ID NO:18) (SEQ ID NO:20) (SEQ ID NO:22) Li05 N=CTTACGCTATGGGT N-TCTATCGTTrCTTCTGGTGGCT N=GAGGGTGACCATAATGCTTTT (SEQ ID NO:17) ATACTGATTATGCTGACTCCGTTAAAGGT GATATC (SEQ IDNO:19) (SEQ ID NO:21) P=SYAMY P=SISTSGGYTGYADSVKG P=DTSDNDYYYMDV (SEQ ID NO:24) (SEQ ID NO:26) (SEQ ID NO:28) Lill N=TCTTACGCTATGTAT N=TCTATCTCTACTTCTGGTGGCTA N=GATACCAGCGATAATGAC (SEQ ID NO:23) TACTGGTTATGCTGACTCCGTTAAAGGT TACTACTACATGGACGTC (SEQ ID NO:25) (SEQ ID NO:27) Li01 P=KYQMT P=SIYPSGGNTVYADSVKG P=GTTEAVFDY ________ (SEQ ID NO:30) (SEQ ID NO:32) (SEQ ID NO:34) -50 Antibody Name VH-CDR1 VH-CDR2 VH-CDR3 N==AAGTACCAGATGAC' N=TCTATCTATCCTTCTGGTGGCAA N=GGGACTACAGAGGCAGTCTT (SEQ ID NO:29) TACTGTTTATGCTGACTCCGTTAAAGGT TGACTAC (SEQ ID NO:31) (SEQ ID NO:33) P=QYNMF P=RISSSOGMTMYADSVKG P=EALRPYCSGGSCYSDYYYYGMDV (SEQ ID NO:36) (SEQ ID NO:38) (SEQ ID NO:40) N= CAGTACAATATGTTT N= CGTATCTCTTCTTCTGGTGGCAT N=GAAGCGTTACGGCCTrATTG Lil2 (SEQ ID NO:35) GACTATGTATGCTGACTCCGTrAAAGGT TAGTGGTGGTAGCTGCTACTCCG (SEQ ID NO:37) ACTACTACTACTACGGTATGGAC GTC (SEQ ID NO:39) P=EYPMD P=SIYSSGGSTVYADSIKG P=EGDSDAFDI (SEQ ID NO:42) (SEQ ID NO:44) (SEQ ID NO:46) LU06 N=GAGGGTGACTCTGATGCTTTT N=GAGTACCCTATGGAT N=TCTATCTATTCTTCTGGTGGCTC GATATC (SEQ ID NO:41) TACTGTTTATGCTGACTCCATTAAAGGT (SEQ ID NO:45) (SEQ ID NO:43) P=HYEMV (SEQ ID NO:48 P=SIRSSGGATKYADSVKG (SEQ ID NO:50) P=ESPDDYFDY (SEQ ID NO:52 i08 N= CATTACGAGATGGTT N= TCTATCCGTTCTTCTGGTGGCGCTAC N= GAGTCGCCAGACGACTACTTT (SEQ ID NO:47) TAAGTATGCTGACTCCGTTAAAGGT GACTAC (SEQ ID NO:51) (SEQ ID NO:49) P=QYPME (SEQ ID NO:54) P=GIYPSGGSTVYADSVKG (SEQ ID NO:56) P=AGQWLGDFDY (SEQ ID NO:58) N=CAGTACCCTATGGAG N-GGTATCTATCCTTCTGGTGGCTCTA N=GCGGGGCAGTGGCTGGGGGAC Li03 (SEQ ID NO:53) CTGTTTATGCTGACTCCGTTAAAGGT TTTGACTAC (SEQ ID NO:55) (SEQ ID NO:57) P=MYSMV P=YISPSGGKTMYADSVKG P=DSRRRYYDFWSGYHNYYYYYMDV (SEQ ID NO:60) (SEQ ID NO:62) (SEQ ID NO:64) L09 N=ATGTACTCTATGGTT N=TATATCTCTCCTTCTGGTGOCAAG N=GATTCGAGACGCCGGTATTACGA (SEQ ID NO:59) ACTATGTATGCTGACTCCGTTAAAGGT TTTTTGGAGTGGTTATCACAACTACT (SEQ ID NO:61) ACTACTACTACATGGACGTC (SEQ ID NO:63) P=RYNMG P=VIYPSGGGTHYADSVKG P=SIADDAFDI (SEQ ID NO:66) (SEQ ID NO:68) (SEQ ID NO:70) Li04 N=CGTTACAATATGGGT N=GTTATCTATCCTTCTGGTGGCGOT N=TCTATAGCAGATGATGCTTTTGATATC (SEQ ID NO:65) ACTCATTATGCTGACTCCGTTAAAGGT (SEQ ID NO:69) (SEQ ID NO:67) P-TYEMI P-SIGPSGGLTWYADSVKG P=MYYCVRIDDSSGWAFDI (SEQ ID NO:72) (SEQ ID NO:74) (SEQ ID NO:76) Li02 N=ACTTACGAGATGATT N=TCTATCGGTCCTTCTGGTGGCC N=ATGTATTACTGTGTACGGATTGATGA (SEQ ID NO:71) TTACTTGGTATGCTGACTCCGTTAAA TAGTAGTGGTTGGGCTTGATATC (SEQ ID NO:73) (SEQ ID NO:75) P=HYEMY (SEQ ID P=RIVSSGGFTKYADSVKG Lil3 NO:389) (SEQ IDNO:390) P=EGDNDAFDI (SEQ ID NO:391) P=AYMMQ P=SISPSGGNTKYADSVKG Li32 (SEQ ID NO:395) (SEQ ID NO:396) P=GDYGYWFDP (SEQ ID NO:397) P=lYPMF (SEQ ID P=WIGPSGGITKYADSVKG Li33 NO:401) (SEQ ID NO:402) P=EGHNDWYFDL (SEQ ID NO:403) P=NYEMY (SEQ ID P=GIYSSGGITVYADSVKG Li34 NO:407) (SEQ ID NO:408) P=AAILDWYFDL (SEQ ID NO:409) 1A47 P=NYGMN P=WITDTGEPTYTEDFQG P=EGVHFDY (SEQ ID NO:77) (SEQ ID NO:78) (SEQ ID NO:79) 2F3 P=FSDAWLD P=EIRSKANNHATNYAESVKG P=SFAY (SEQ ID NO:80) (SEQ ID NO:81) (SEQ ID NO:82) 3PID10.2C3 P=SSWTQ P=AIYPGDGDTRYTQKFKG P=HNSYGMDY and (SEQ ID NO:83) (SEQ ID NO:84) (SEQ ID NO:85) 3PIEll.3B7 Lla.01 P=GYSFTNYWIG P=IIDPDDSYTTYSPSFQG P=AEFYWGAYDG (SEQ ID NO:195) (SEQ ID NO:196) (SEQ ID NO:197) Lla.02 P=GGSIRGNYWS P=SINYSGFTNPSLKG P=VRHWYFDV (SEQ ID NO:198) (SEQ ID NO:199) (SEQ ID NO:200) Lla.03 P=GYTFNGFDMH P=WIDPYNGSTTYAQKFQG P=DFYMDGHYYIFDV (SEQ ID NO:201) (SEQ ID NO:202) (SEQ ID NO:203) Lla.04 P-GYSFSNYYIH P=IIDPGDSFTSYSPSFQG P=DLAWIDYGFDY (SEQ ID NO:204) (SEQ ID NO:205) (SEQ ID NO:206) P=GFTFTSHTVS P-SITGNGSTTYYADSVKG P=FYGDFDS (SEQ ID NO:207) (SEQ ID NO:208) (SEQ ID NO:209) P=GFTFSSNWMS P=TIFYSGSSTYYADSVKG P=DLPMKGFIQQRYGFDDV (SEQ ID NO:210) (SEQ ID NO:21 1) (SEQ ID NO:212) -.51 Antibody Name VH-CDR1 VH-CDR2 VH-CDR3 Lla.07 P=GFTFSGYAIS P=TIWGSGSTTYYADSVKG P=EYWYYDQFTAV (SEQ ID NO:213) (SEQ ID NO:214) (SEQ IDNO:215) 08 P=GDSVSSNSAAWS P=RIYYRSKWYNDYAVSVKS P-=EVYSAGIMDY (SEQ ID NO:216) (SEQ ID NO:217) (SEQ ID NO:218) Lla.09 P=GYSFTNHWIG P=IDPSDSDTNYSPSFQG P=GFYGIADTFDV (SEQ ID NO:219) (SEQ ID NO:220) (SEQ ID NO:221) Lla.10 P=GYSFTNYWIA P=MIYPDDSNTNYSPSFQG P=TNYLGFYDS (SEQ ID NO:222) (SEQ ID NO:223) (SEQ ID NO:224) Lla.11 P=GFTFSDYGIS P=NILYDGSETYYADSVKG P=GYPTDDYSFDI (SEQ ID NO:225) (SEQ ID NO:226) (SEQ ID NO:227) L~a.12 P=GDSVSDNSAAWG P=R1YYRSKWYNDYAVSVKS P=GRHEYGGLGYAEAMDH (SEQ ID NO:228) (SEQ ID NO:229) (SEQ ID NO:230) Lla.13 P=GFTFSSYAMS P=AISGSGGSTYYADSVKG P=HYTYMHFEDY (SEQ ID NO:231) (SEQ ID NO:232) (SEQ ID NO:233) *Determined by the Kabat system (see supra). N=nucleotide sequence, P=polypeptide sequence. In certain embodiments, an antibody or antigen-binding fragment comprising the VH encoded by the polynucleotide specifically or preferentially binds to Sp35. [01781 In another embodiment, the present invention provides an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid encoding an immunoglobulin heavy chain variable region (VH) in which the CDR1, CDR2, and CDR3 regions have polypeptide sequences which are identical to the CDR1, CDR2, and CDR3 groups shown in Table 4. In certain embodiments, an antibody or antigen-binding fragment comprising the VH encoded by the polynucleotide specifically or preferentially binds to Sp35. [0179] In a further aspect, the present invention provides an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid encoding an immunoglobulin heavy chain variable region (VH) in which the CDR1, CDR2, and CDR3 regions are encoded by nucleotide sequences which are identical to the nucleotide sequences which encode the CDR1, CDR2, and CDR3 groups shown in Table 4. In certain embodiments, an antibody or antigen-binding fragment comprising the VH encoded by the polynucleotide specifically or preferentially binds to Sp35. [0180] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VH encoded by one or more of the polynucleotides described above specifically or preferentially binds to the same epitope as a monoclonal antibody selected from the group consisting of: 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3P1D10.2C3, 3PlEll.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (Li022), 35-E04 (Li033), 36-C09 (Li04), 30-Al1 (Li05), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (LiO8), 36-A12 (LiO9), 28-D02 (LilO), 30-BOl (Lil 1), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13), or will competitively inhibit such a monoclonal antibody from binding to Sp35.

- 52 [0181] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VH encoded by one or more of the polynucleotides described above specifically or preferentially binds to an Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no greater than 5 x 10-2 M, 10- 2 M, 5 x 10~ 3 M, 10-3 M, 5 x 10-4 M, 10 4 M, 5 x 10~5 M, 10-' M, 5 x 106 M, 10-' M, 5 x 10~7 M, 10~7 M, 5 x 10~ M, 10~ M, 5 x 10~9 M, 10~9 M, 5 x 1010 M, 10410 M, 5 x 10~1 M, 10-" M, 5 x 10 12 M, 1012 M, 5 x 1013 M, 10-1 M, 5 x 10-4 M, 10~4 M, 5 x 1015 M, or 10~15 M. [01821 In another embodiment, the present invention provides an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid encoding an immunoglobulin light chain variable region (VL), where at least one of the CDRs of the light chain variable region or at least two of the CDRs of the light chain variable region are at least 80%, 85%, 90% or 95% identical to reference light chain CDRI, CDR2, or CDR3 amino acid sequences from monoclonal Sp35 antibodies disclosed herein. Alternatively, the CDR1, CDR2, and CDR3 regions of the VL are at least 80%, 85%, 90% or 95% identical to reference light chain CDR1, CDR2, and CDR3 amino acid sequences from monoclonal Sp35 antibodies disclosed herein. Thus, according to this embodiment a light chain variable region of the invention has CDR1, CDR2, or CDR3 polypeptide sequences related to the polypeptide sequences shown in Table 5: TABLE 5: Reference VL CDRI, CDR2, and CDR3 amino acid sequences* Antibody Name VL-CDR1 VL-CDR2 VL-CDR3 P=RASQGIGNWLA P=AASSLES P=QQAQTFPLT (SEQ ID NO:87) (SEQ ID NO:89) (SEQ ID NO:91) N=CGGGCGAGTCAGGG N=GCTGCATCCAGTTTGGAAAGT N CAACAGGCTCAGAC TATTGGCAACTGGTrAGCC (SEQ IDNO:88) TTTCCCGCTCACC (SEQ ID NO:86) (SEQ IDNO:90) Lil0 P=SGDQLGDKHVA P=-LDIKRPA P=QAWDIKTV (SEQ ID NO:93) (SEQ ID NO:95) (SEQ ID NO:97) N=TCTGGAGATCAGTTG N=CTAGACATTAAGAGGCCCGCA N=CAGGCGTGGGACATC GGTGACAAACATGTGGCT (SEQ ID NO:94) AAGACGGTC (SEQ ID NO:96) (SEQ ID NO:92) Li07 P=GGDNIGSKSVH P=DDYDRPS P=QVRDSRTEERV (SEQ ID NO:99) (SEQ ID NO:101) (SEQ IDNO:103) N=GGGGGAGACAACAT N=GATGATTATGACCGGCCCTCA N=CAGGTGAGGGACAGCCG TGGAAGTAAGAGTGTCCAC (SEQ ID NO:100) TACTGAGGAACGGGTG (SEQ ID NO:98) (SEQ ID NO:102) Li05 P=RASQEIANYLA P=DTYTLQT P=QQADIFPLS (SEQ ID NO:105) (SEQ ID NO:107) (SEQ ID NO:109) N=CGGGCGAGTCAGGAG N--GATACATACACTTTGCAGACT N=CAACAGGCTGACATTTr ATTGCCAACTACTTAGCC (SEQ ID NO:106) CCCGCTCTCT (SEQ ID NO:104) (SEQ ID NO:108) Lill P=QASQDISNYLN P=DASNLET P=QQADRFPAVT (SEQ ID NO:111) (SEQ ID NO:113) (SEQ ID NO:1 15) N=CAGGCGAGTCAGGA N=GATGCATCCAATTTGGAAACA N=CAACAGGCTGACAGGTrC CATTAGCAACTATTTAAAT (SEQ ID NO:112) CCTGCGGTCACT (SEQ ID NO:110) (SEQ IDNO:114) Li01 IIII - 53 Antibody Name VL-CDR1 VL-CDR2 VL-CDR3 P=RASQSISSWLA P=AASSLRT P=LQDYSYPLT (SEQ ID NO: 17) (SEQ ID NO:119) (SEQ ID NO:121) N=CGGGCCAGTCAGAGTA N=GCTGCATCCAGTTTACGAACT N=CTACAAGATTACAGTTAC TTAGTAGCTGGTTGGCC (SEQ ID NO:118) CCTCTCACT Li06 (SEQ ID NO:116) (SEQ ID NO:120) P=QASQDISYYLN P=DVSNLQT P=QQSDNLPLT (SEQ ID NO:123) (SEQ ID NO:125) (SEQ ID NO:127) N-CAGGCGAGTCAGGAC N=GATGTATCCAATTTGCAAACA N=CAACAGTCTGATA ATTAGTTACTATTTAAAT (SEQ ID NO:124) ATCTCCCTCTCACT U08 (SEQ IDNO:122) (SEQ ID NO:126) P=RASQSISSYLN P=AASSLQS P=QQSYSTPWT (SEQ ID NO:129) (SEQ ID NO:131) (SEQ ID NO:133) N=GGGCAAGTCAGAGC N=GCTGCATCCAGTTTGCAAAGT N=CAACAGAGTTACA ATTAGCAGCTATTTAAAT (SEQ ID NO:130) GTACCCCGTGGACG L03 (SEQ ID NO:128) (SEQ ID NO:132) P=RASQSIDTYLN P=AASKLED P=QQSYSPPLT (SEQ IDNO:135) (SEQ IDNO:137) (SEQ IDNO:139) N=CGCGCAAGTCAGAGC N=GCTGCATCCAAGTTGGAAGAC N=CAACAGAGTTACAG ATCGACACCTATTTAAAT (SEQ ID NO:136) TCCCCCTCTCAC Li09 (SEQ ID NO:134) (SEQ ID NO:138) P=SGDKLGDKFAS P=QDRKRLS P=QAWDTNTVV (SEQ IDNO:141) (SEQ ID NO:143) (SEQ ID NO:145) N=TCTGGAGATAAATTGG N-CAAGATAGGAAGCGTCTCTCA N=CAGGCGTGGGACA GGGATAAATTTGCTTCC (SEQ ID NO:142) CCAACACTGTGGTC L02 (SEQ ID NO:140) (SEQ ID NO:144) P=RASQSVSSYLA P=DASNRAT (SEQ ID NO:387) P=QQRSNWPMYT (SEQ ID NO:388) U1l3 (SEQ ID NO:386) P=QASQDISYYLN P=DAFILEG (SEQ ID NO:393) P=QQSDQLPVT (SEQ ID NO:394) Ui32 (SEQ ID NO:392) P=RASQSVSSYLA P=DASNRAT (SEQ ID NO:399) P=QQYDKWPLT (SEQ ID NO:400) Ui33 (SEQ ID NO:398) P=HASQDISNYLS P DAFNLET (SEQ ID NO:405) P=QHYDNLPFT (SEQ ID NO:406) Li34 (SEQ ID NO:404) P=SASSSVSYMH P=DTSKLAS P=QQWSSNPFT 1A47 (SEQIDNO:146) (SAQIDNO:147) (SEQ ID NO:148) P=RASGNIYNYLA P=NAKTLPD P=QHFWAIPYT 2F3 (SEQ ID NO:149) (SEQ ID NO:150) (SEQ ID NO:151) P=KSSQSLLNSGNQKNYLT P=WASTRES P=QNDYSYPLFT 3PID10.2C3 (SEQ ID NO: 152) (SEQ ID NO:153) (SEQID NO:154) P--KSSQSLLNSGNQKSYLT P=WASTRES P=QNDYSYPLFT 3P-E1I.3B7 (SEQ ID NO:155) (SEQ ID NO:156) (SEQ ID NO:157) P=SGDSLPSKFVH P=RDNNRPS P=SSYDALTD Lla.01 (SEQ ID NO:234) (SEQ ID NO:235) (SEQ ID NO:236) P=RASQSITNSYLG P=DASSRAT P=QQASDAPE Lla.02 (SEQ ID NO:237) (SEQ ID NO:238) (SEQ ID NO:239) P=RASQGINFWLN P=AGSNLQS P=MQDSDFPF Lla.03 (SEQ ID NO:240) (SEQ ID NO:241) (SEQ ID NO:242) P=TGSSSNIGAGYDVS P=RNNNRPS P=QTYDNSTD Lla.04 (SEQ ID NO:243) (SEQ ID NO:244) (SEQ D NO:245) P=SGDNIRSYYVH P=EDSNRPS P=QSYDSAILLH Lla.05 (SEQ ID NO:246) (SEQ ID NO:247) (SEQ ID NO:248) P=RSSQSLVLRTGYTYLN P=LVSNRAS P=QQYYGMPL Lla.06 (SEQ ID NO-249) (SEQ ID NO:250) (SEQ ID NO:251) P=RASQSVSYQYLA P=GASSRAT P=QQYGSVPR Lla.07 (SEQ ID NO:252) (SEQ ID NO:253) (SEQ ID NO:254) P=SGDSLGSYYVH P=DDNDRPS P=SAYDYSART Lla.08 (SEQ ID NO:255) (SEQ ID NO:256) (SEQ ID NO:257) P=SGDNLGSKYVS P=DDDDRPS P=SSYDFLNIGL Lla.09 (SEQ ID NO:258) (SEQ ID NO:259) (SEQ ID NO :260) P=SGDSLGKKSVH P=EDSERPS P=SSYTNSVD Lla.10 (SEQ ID NO:261) (SEQ ID NO:262) (SEQ ID NO:263) P-SGDNLGKKYVG P=DDDNRPS P=QSYDDTSI La.ll (SEQ ID NO:264) (SEQ IDNO:265) (SEQ ID NO:266) P=SGDSLGNKYVH P=DDSDRPS P=QTWDYVGY Lla.12 (SEQ ID NO:267) (SEQ ID NO:268) (SEQ ID NO:269) - 54 Antibody Name VL-CDR1 VL-CDR2 VL-CDR3 P=TGTSSDVGGYNYVS P=DVSNRPS P=QSYDRYRLKN Lla.13 (SEQ ID NO:270) (SEQ ID NO:271) (SEQ ID NO:272) *Determined by the Kabat system (see supra). N=nucleotide sequence, P=polypeptide sequence. In certain embodiments, an antibody or antigen-binding fragment comprising the VL encoded by the polynucleotide specifically or preferentially binds to Sp35. [01831 In another embodiment, the present invention provides an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid encoding an immunoglobulin light chain variable region (VL) in which the CDR1, CDR2, and CDR3 regions have polypeptide sequences which are identical to the CDR1, CDR2, and CDR3 groups shown in Table 5. In certain embodiments, an antibody or antigen-binding fragment comprising the VL encoded by the polynucleotide specifically or preferentially binds to Sp35. [01841 In a further aspect, the present invention provides an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid encoding an immunoglobulin light chain variable region (VL) in which the CDR1, CDR2, and CDR3 regions are encoded by nucleotide sequences which are identical to the nucleotide sequences which encode the CDR1, CDR2, and CDR3 groups shown in Table 5. In certain embodiments, an antibody or antigen-binding fragment comprising the VL encoded by the polynucleotide specifically or preferentially binds to Sp35. [01851 In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VL encoded by one or more of the polynucleotides described above specifically or preferentially binds to the same epitope as a monoclonal antibody selected- from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3P1D1O.2C3, 3PlEl1.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (LiO2), 35-E04 (Li03), 36-C09 (LiO4), 30-All (Li05), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (LiO8), 36-A12 (LiO9), 28-D02 (LilO), 30-BOl (Lil 1), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla. 13), or will competitively inhibit such a monoclonal antibody from binding to Sp35. [01861 In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VL encoded by one or more of the polynucleotides described above specifically or preferentially binds to an Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no greater than 5 x 10 2 M, 102 M, 5 x 10 3 M, 10-3 M, 5 x 10 M, 104 M, 5 x 10-5 M, 10-5 M, 5 x 10- 6 M, 10- 6 M, 5 x - 55 10~7 M, 10~7 M, 5 x 108 M, 10~" M, 5 x 109 M, 10- M, 5 x 10-* M, 1010 M, 5 x 10~" M, 10~" M, 5 x 10 12 M, 1012 M, 5 x 10-3 M, 10-3 M, 5 x 10-44 M, 10-4 M, 5 x 10-" M, or 10-1 M. [0187] In a further embodiment, the present invention includes an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid encoding a VH at least 80%, 85%, 90% or 95% identical to a reference VH polypeptide sequence selected from the group consisting of SEQ ID NOs: 158 to 172, 372, 376, 380, and 384 shown in Table 6. In certain embodiments, an antibody or antigen-binding fragment comprising the VH encoded by the polynucleotide specifically or preferentially binds to Sp35. [0188] In another aspect, the present invention includes an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid sequence encoding a VH having a polypeptide sequence selected from the group consisting of SEQ ID NOs: 158 to 172, 372, 376, 380 and 384 shown in Table 6. In certain embodiments, an antibody or antigen-binding fragment comprising the VH encoded by the polynucleotide specifically or preferentially binds to Sp35. TABLE 6 - VH Polypeptide Sequences VH Sequence SEQ ID NO: Li02 EVQLLESGGGLVQPGGSLRLSCAASGFTFSTYEMIWVRQAPGKGLEWVSSIGP 158 SGGLTWYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAMYYCVRIDDSSGW AFDIWGQGTTVTVSSASTKGPSVFPLAP Li09 EVQLLESGGGLVQPGGSLRLSCAASGFTFSMYSMVWVRQAPGKGLEWVSYIS 159 PSGGKTMYADSVKGRFTISRDNSKNTFYLQMNSLRAEDTAVYYCARDSRRRY YDFWSGYINYYYYYMDVWGKGTTVTVSSASTKGPSVFPLAP Li06 EVQLLESGGGLVQPGGSLRLSCAASGFTFSEYPMDWVRQAPGKGLEWVSSIY 160 SSGGSTVYADSIKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAREGDSDAF D1WGQGTMVTVSSASTKGPSVFPLAP L05 EVQLLESGGGLVQPGGSLRLSCAASGFTFSAYAMGWVRQAPGKGLEWVSSIV 161 SSGGYTDYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCAREGDHNA FDIWGQGTMVTVSSASTKGPSVFPLAP Li04 EVQLLESGGGLVQPGGSLRLSCAASGFTFSRYNMGWVRQAPGKGLEWVSVIY 162 PSGGGTHYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCASSIADDAF

DIWGQGTMVTVSSASTKGPSVFPLAP

-56 VH Sequence SEQ NO: Li08 EVQLLESGGGLVQPGGSLRLSCAASGFTFSHYEMVWVRQAPGKGLEWVSSIRS 163 SGGATKYADSVKGRFTISRDNSKNTLYLQMINSLRAEDTAVYYCAKESPDDYF DYWGQGTLVTVSSASTKGPSVFPLAP Lill EVQLLESGGGLVQPGGSLRLSCAASGFTFSSYAMYWVRQAPGKGLEWVSSIST 164 SGGYTGYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARDTSDNDY YYMDVWGKGTTVTVSSASTKGPSVFPLAP 110 EVQLLESGGGLVQPGGSLRLSCAASGFTFSTYPMVWVRQAPGKGLEWVSWIG 165 PSGGVTAYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARPYSSGW WDFDLWGRGTLVTVSSASTKGPSVFPLAP LiOl EVQLLESGGGLVQPGGSLLSCAASGFTFSKYQMTWVRQAPGKGLEWVSSIY 166 PSGGNTVYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCASGTTEAV FDYWGQGTLVTVSSASTKGPSVFPLAP 1i07 EVQLLESGGGVQPGGSLRLCWVRQAPGKGLEWVSSIS 167 PSGGFTSYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARDRHAFD IWGQGTMVTVSSASTKGPSVFPLAP Li03 EVQLLESGGGLVQPGGSLRLSC SGFFSQYPMEWVRQAPGKGLEWVSG1Y 168 PSGGSTVYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARAGQWL GDFDYWGQGTLVTVSSASTKGPSVFPLAP Lil2 EVQLLESGGGLVQPGGSLRLSCAASGFTFSQYNMFWVRQAPGKGLEWVSRISS 169 SGGMTMYADSVKGRFTSRDNSKNTLYLQMNSLRAEDTAVYYCAREALRPY CSGGSCYSDYYYYGMDVWGQGTTVTVSSASTKGPSVFPLAP 1A7 QVQLVQSGPELKKPGETVKISCKASGYTFTNYGMNWVKQAPGKGLKWMGW 170 INTDTGEPTYTEDFQGRFAFSLETSASTVYLQFNNLKNEDTATYFCAR-EGVIHF DYWGQGTTVTVSS 2F3 EVKLEESGGGLVQPGGSMKLSCAASGFTFSDAWLDWVRQSPEKGLEWVAEIR 171 SKANNHATNYAESVKGRFTISRDDSKSSVYLQMNSLRAEDTGIYFCTPSFAYW

GQGTTVTVSS

-57 VH Sequence SEQ ID NO: 3PiD QVQLQQSGAELARPGASVKLSCRASGYTFTSSWTQWVKQRPGQGLEWIGAIY 172 10.2C PGDGDTRYTQKFKGKATLTADKSSSTAYMQLSSLASEDSAVYYCARHNSYG 3 MDYWGQGTSVTVSS and 3P1E 11.3B 7 Li13 EVQLLESGGGLVQPGGSLRLSCAASGFTFSHYEMYWVRQAPGKGLEWVSRIV 372 SSGGFTKYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCATEGDNDA FDIWGQGTTVTVSS Li32 EVQLLESGGGLVQPGGSLRLSCAASGFTFSAYMMQWVRQAPGKGLEWVSSIS 376 PSGGNTKYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARGDYGY WFDPWGQGTLVTVSS Li33 EVQLLESGGGLVQPGGSLRLSCAASGFTFSIYPMFWVRQAPGKGLEWVSWIGP 380 SGGITKYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTATYYCAREGHNDWY FDLWGRGTLVTVSS Li34 EVQLLESGGGLVQPGGSLRLSCAASGFTFSNYEMYWVRQAPGKGLEWVSGIY 384 SSGGITVYADSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARAAILDW YFDLWGRGTLVTVSS 1__ [0189] In a further embodiment, the present invention includes an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid encoding a VH at least 80%, 85%, 90% or 95% identical to a reference VH polypeptide sequence selected from the group consisting of SEQ ID NOs: 158-172, 372, 376, 380, and 384. In certain embodiments, an antibody or antigen binding fragment comprising the VH encoded by the polynucleotide specifically or preferentially binds to Sp35. [01901 In another aspect, the present invention includes an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid sequence encoding a VH of the invention, selected from the group consisting of SEQ ID NOs: 158-172, 372, 376, 380, and 384. In certain embodiments, an antibody or antigen-binding fragment comprising the VH encoded by the polynucleotide specifically or preferentially binds to Sp35. [0191] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VH encoded by one or more of the polynucleotides described above specifically or preferentially binds to the same epitope as a monoclonal antibody selected from the group consisting of,(201') 3A3, 3A6, 1A7, 1G7, 2B10, 2C1 1, 2F3, 3P1D10.2C3, 3P1E11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (LiO2), 35-E04 (Li03), 36-C09 (Li04), 30-All (Li05), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (Li08), 36-A12 (Li09), 28-D02 (LilO), 30-BOI (Lill ), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 -58 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13), or will competitively inhibit such a monoclonal antibody from binding to Sp35. [0192] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VH encoded by one or more of the polynucleotides described above specifically or preferentially binds to an Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no greater than 5 x 10-2 M, 10-2 M, 5 x 10~3 M, 10- M, 5 x 104 M, 10~4 M, 5 x 10-5 M, 10-' M, 5 x 10- M, 106 M, 5 x 10-7 M, 10- M, 5 x 108 M, 10I M, 5 x 109 M, 10- M, 5 x 1010 M, 1010 M, 5 x 10~" M, 10~" M, 5 x 10 1 M, 10-2 M,5x 10 13 M, 10-1 M,5x 10 4 M, 10 14 M,5x 10' 5 M, or 10-' M. [0193] In additional embodiments, the present invention includes an isolated polynucleotide which encodes a heavy chain variable region (VH), where the polynucleotide comprises a VH nucleic acid sequence selected from the group consisting of SEQ ID NOs 173 to 184, 370, 374, 378 and 382, as shown in Table 7. In certain embodiments, an antibody or antigen-binding fragment comprising the VH encoded by the polynucleotide specifically or preferentially binds to Sp35. TABLE 7 - VH Polynucleotide Sequences VH Sequence SEQ ID NO: LiO2 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTAC 173 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTACTTACGAGATGATTTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTTCTATCGGTCCTTCTGGT GGCCTTACTTGGTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACCGC CATGTATTACTGTGTACGGATTGATGATAGTAGTGGTTGGGCTTTTGATATCTGG GGCCAAGGGACCACGGTCACCGTCTCAAGCGCCTCCACCAAGGGCCCATCGGTCT TCCCGCTAGCACCC Li09 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTAC 174 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTATGTACTCTATGGTTTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTTATATCTCTCCTTCTGGT GGCAAGACTATGTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTTTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACGGC CGTGTATTACTGTGCGAGAGATTCGAGACGCCGGTATTACGATTTTTGGAGTGGT TATCACAACTACTACTACTACTACATGGACGTCTGGGGCAAAGGGACCACGGTCA CCGTCTCAAGCGCCTCCACCAAGGGCCCATCGGTCTTCCCGCTAGCACCC Li06 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTAC 175 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTGAGTACCCTATGGATTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTTCTATCTATTCTTCTGGT GGCTCTACTGTTTATGCTGACTCCATTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACGGC CGTGTATTACTGTGCCAGAGAGGGTGACTCTGATGCTTTTGATATCTGGGGCCAA GGGACAATGGTCACCGTCTCAAGCGCCTCCACCAAGGGCCCATCGGTCTTCCCGC

TAGCACCC

-59 VH Sequence SEQ IDNO: Li05 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTAC 176 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTGCTTACGCTATGGGTTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTTCTATCGTTTCTTCTGGT GGCTATACTGATTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACGGC CGTGTATTACTGTGCCAGAGAGGGTGACCATAATGCTTTTGATATCTGGGGCCAA GGGACAATGGTCACCGTCTCAAGCGCCTCCACCAAGGGCCCATCGGTCTTCCCGC TAGCACCC Li04 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTAC 177 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCCGTTACAATATGGGTTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTGTTATCTATCCTTCTGGT GGCGGTACTCATTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACGGC CGTGTATTACTGTGCGAGTTCTATAGCAGATGATGCTTTTGATATCTGGGGCCAA GGGACAATGGTCACCGTCTCAAGCGCCTCCACCAAGGGCCCATCGGTCTTCCCGC TAGCACCC Li08 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTAC 178 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTCATTACGAGATGGTTTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTTCTATCCGTTCTTCTGGT GGCGCTACTAAGTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACGGC CGTGTATTACTGTGCGAAAGAGTCGCCAGACGACTACTTTGACTACTGGGGCCAG GGAACCCTGGTCACCGTCTCAAGCGCCTCCACCAAGGGCCCATCGGTCTTCCCGC TAGCACCC Lill GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTAC 179 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTTCTTACGCTATGTATTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTTCTATCTCTACTTCTGGT GGCTATACTGGTTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACGGC CGTGTATTACTGTGCGAGAGATACCAGCGATAATGACTACTACTACATGGACGTC TGGGGCAAAGGGACCACGGTCACCGTCTCAAGCGCCTCCACCAAGGGCCCATCGG TCTTCCCGCTAGCACCC LilO GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTAC 180 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTACTTACCCTATGGTTTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTTGGATCGGTCCTTCTGGT GGCGTTACTGCTTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACGGC CGTGTATTACTGTGCGAGACCCTATAGCAGTGGCTGGTGGGACTTCGATCTCTGG GGCCGTGGCACCCTGGTCACCGTCTCAAGCGCCTCCACCAAGGGCCCATCGGTCT TCCCGCTAGCACCC LiO1 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTT'ITTAC 181 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTAAGTACCAGATGACTTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTTCTATCTATCCTTCTGGT GGCAATACTGTTTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACGGC CGTGTATTACTGTGCGAGTGGGACTACAGAGGCAGTCTTTGACTACTGGGGCCAG GGAACCCTGGTCACCGTCTCAAGCGCCTCCACCAAGGGCCCATCGGTCTTCCCGC

TAGCACCC

-60 VH Sequence SEQ ID NO: Li07 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTAC 182 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTATGTACTTTATGGGTTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTTCTATCTCTCCTTCTGGT GGCTTTACTTCTTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACTGC AGTCTACTATTGTGCGAGAGATCGGCATGCTTTTGATATCTGGGGCCAAGGGACA ATGGTCACCGTCTCAAGCGCCTCCACCAAGGGCCCATCGGTCTTCCCGCTAGCAC cc Li03 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTAC 183 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTCAGTACCCTATGGAGTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTGGTATCTATCCTTCTGGT GGCTCTACTGTTTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACGGC CGTGTATTACTGTGCGAGAGCGGGGCAGTGGCTGGGGGACTTTGACTACTGGGGC CAGGGAACCCTGGTCACCGTCTCAAGCGCCTCCACCAAGGGCCCATCGGTCTTCC CGCTAGCACCC Li12 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTAC 184 GTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCAGTACAATATGTTTTGGGT TCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTCGTATCTCTTCTTCTGGT GGCATGACTATGTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGAGACA ACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGACACGGC TGTGTATTACTGTGCGAGAGAAGCGTTACGGCCTTATTGTAGTGGTGGTAGCTGC TACTCCGACTACTACTACTACGGTATGGACGTCTGGGGCCAAGGACCACGGTCA CCGTCTCAAGCGCCTCCACCAAGGGCCCATCGGTCTTCCCGCTAGCACCC Li13 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTA 370 CGTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTCATTACGAGATGTATTGG GTTCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTCGTATCGTTTCTTCT GGTGGCTTTACTAAGTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGA GACAACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGAC ACGGCCGTGTATTACTGTGCAACAGAGGGTGATAATGATGCTTTTGATATCTGG GGCCAAGGGACCACGGTCACCGTCTCAAGC Li32 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTA 374 CGTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTGCTTACATGATGCAGTGG GTTCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTTCTATCTCTCCTTCT GGTGGCAATACTAAGTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGA GACAACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGAC ACGGCCGTGTATTACTGTGCGAGAGGAGATTATGGATACTGGTTCGACCCCTGG GGCCAGGGCACCCTGGTCACCGTCTCAAGC Li33 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTA 378 CGTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTATTTACCCTATGTTTTGG GTTCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTTGGATCGGTCCTTCT GGTGGCATTACTAAGTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGA GACAACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGAC ACAGCCACATATTACTGTGCGAGAGAGGGGCATAACGACTGGTACTTCGATCTC TGGGGCCGTGGCACCCTGGTCACCGTCTCAAGC Li34 GAAGTTCAATTGTTAGAGTCTGGTGGCGGTCTTGTTCAGCCTGGTGGTTCTTTA 382 CGTCTTTCTTGCGCTGCTTCCGGATTCACTTTCTCTAATTACGAGATGTATTGG GTTCGCCAAGCTCCTGGTAAAGGTTTGGAGTGGGTTTCTGGTATCTATTCTTCT GGTGGCATTACTGTTTATGCTGACTCCGTTAAAGGTCGCTTCACTATCTCTAGA GACAACTCTAAGAATACTCTCTACTTGCAGATGAACAGCTTAAGGGCTGAGGAC ACGGCCGTGTATTACTGTGCTAGGGCAGCCATCCTCGACTGGTACTTCGATCTC

TGGGGCCGTGGCACCCTGGTCACCGTCTCAAGC

-61 [0194] In a further embodiment, the present invention includes an isolated polynucleotide comprising, consisting essentially of, or consisting of a VH-encoding nucleic acid at least 80%, 85%, 90% or 95% identical to a reference nucleic acid sequence selected from the group consisting of SEQ ID NOs: 173-184, 370, 374, 378 and 382 of Table 7. In certain embodiments, the polynucleotide encodes a VH polypeptide which specifically or preferentially binds to Sp35. [01951 In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VH encoded by one or more of the polynucleotides described above specifically or preferentially binds to the same epitope as a monoclonal antibody selected from the group consisting of,(201') 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3PID10.2C3, 3P1E11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.iD8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (LiO2), 35-E04 (Li03), 36-C09 (LiO4), 30-All (Li05), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (Li08), 36-A12 (Li09), 28-D02 (LilO), 30-B01 (Lil 1), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (L1a.13), or will competitively inhibit such a monoclonal antibody from binding to Sp35. [0196] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VH encoded by one or more of the polynucleotides described above specifically or preferentially binds to an Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no greater than 5 x 10-2 M, 104 M, 5 x 103 M, 10~3 M, 5 x 104 M, 10~4 M, 5 x 10-5 M, 10-5 M, 5 x 10-6 M, 10-6 M, 5 x 104 M, 10~7 M, 5 x 108 M, 10~8 M, 5 x 10-9 M, 10-9 M, 5 x 1010 M, 1010 M, 5 x 10-n1 M, 10~1 M, 5 x 10 12M, 1012 M, 5 x 10-13 M, 10-13 M, 5 x 1014 M, 10-" M, 5 x 10-15 M, or 10-15 M. [0197] In a further embodiment, the present invention includes an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid encoding a VL at least 80%, 85%, 90% or 95% identical to a reference VL polypeptide sequence selected from the group consisting of SEQ ID NOs: 273 to 286, 373, 377, 381 and 385, shown in Table 8. In certain embodiments, an antibody or antigen-binding fragment comprising the VL encoded by the polynucleotide specifically or preferentially binds to Sp35. [01981 In another aspect, the present invention includes an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid sequence encoding a VL having a polypeptide sequence selected from the group consisting of SEQ ID NOs: 273 to 286, 373, 377, 381 and 385, shown in Table 8. In certain embodiments, an antibody or antigen-binding fragment comprising the VL encoded by the polynucleotide specifically or preferentially binds to Sp35.

- 62 TABLE 8 - VL Polypeptide Sequences VL Sequence SEQ ID NO: Li02 FYSHSAQYELTQPPSVSVSPGQTASITCSGDKLGDKFASWYQQKAGQSPVLV 273 IFQDRKRLSGIPERFSGSNSGNTATLTISGTQAMDEADYYCQAWDTNTVVFG GGTKLTVLGQPKAAP Li09 FYSHSAQDIQMTQSPSSLSAFVGDRVAITCRASQSIDTYLNWYQQKPGKAPK 274 LLIYAASKLEDGVPSRFSGSGTGTDFTLTIRSLQPEDFGTYYCQQSYSPPLTFG GGTKVEIKRTVAAP Li06 FYSHSAQDIQMTQSPSTLSASVGDRVTITCRASQSISSWLAWYQQKPGKAPN 275 LLIYAASSLRTGVPSRFRGSGSGTDFTLTISSLQPEDFATYYCLQDYSYPLTFG QGTKLEIKRTVAAP Li05 FYSHSAQSVLTQPPSVSVAPGQTARISCGGDNIGSKSVHWYQQRPGQAPVLV 276 VYDDYDRPSGIPERFSGSNSGDTAILTITRVEVGDEADFYCQVRDSRTEERVF GGGTKVTVLGQPKAAP LiO8 FYSHSAQDIQMTQSPSSLSASVGDRVTITCQASQDISYYLNWYQQKPGKAPK 277 VLIYDVSNLQTGVPSRFSGSASATDFTLTISSLQPEDIATYYCQQSDNLPLTFG GGTKVEIKRTVAAP Lill FYSHSAQDIQMTQSPSSVSAPIGDRVTITCRASQEIANYLAWYQQKPGKAPK 278 LLIYDTYTLQTDVPPRFSGSGSGTDFTLTISSLQPEDTATYFCQQADIFPLSFG GGTKVEIKRTVAAP LilO FYSHSAQDIQMTQSPSSMSASVGDTVTrCRASQGIGNWLAWYQQKPGKAP 279 TLLlYAASSLESGVPSRFTGSGSSSGIDFTLTISDLHPEDLATYYCQQAQTFPLT FGGGTRVDLKRTVAAP LiOl FYSHSAQDIQMTQSPSSLSASVGDRVTITCQASQDISNYLNWYQQKPGKAPK 280 LLIYDASNLETGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQADRFPAVTF GGGTKVEIKRTVAAP Li07 FYSHSAQSELTQPPSVSVSPGQTAIITCSGDQLGDKHVAWYQQKPGQSPVLVI 281 YLDIKRPAGISERFSGSNSGNTATLTIRGTQAMDEADYYCQAWDIKTVFGGG TKLTVLSQPKAAP Li03 FYSHSAQDIQMTQSPSSLSASVGDRVTITCRASQSISSYLNWYQQKPGKAPKL 282 LIYAASSLQSGVPSRFSGSGSGTDFTLTISSLQPEDFATYYCQQSYSTPWTFGQ GTKVEIKRTVAAP 1A7 QIVLTQSPAIMSASPGEKVTMTCSASSSVSYMHWYQQKSGTSPKRWIYDTSK 283 LASGVPARFSGSGSGTSYSLTISSMEAEDAATYYCQQWSSNPFTFGSGTKLEI K 2F3 DIQMTQSPASLSASVGETVTITCRASGNIYNYLAWFQQKQGKSPQLLVYNAK 284 TLPDGVPSRFSGSGSGTQYFLKINSLQPEDFGSYYCQHFWAIPYTFGGGTKLE IKR 3P1D DIVMTQSPSSLTVTAGEKVTMSCKSSQSLLNSGNQKNYLTWYQQKPGQPPK 285 10.2C LLIYWASTRESGVPDRFTGSGSGTDFTLTINSVQAEDLAVYYCQNDYSYPLFT 3 FGSGTKLEIR 3P1E1 DIVMTQSPSSLTVTAGEKVTMSCKSSQSLLNSGNQKSYLTWYQQKPGQPPK 286 1.3B7 LLIYWASTRESGVPDRFTGSGSGTDFTLTINSVQAEDLAVYYCQNDYSYPLF

TFGSGTKLEIR

-63 VL Sequence SEQ ID NO: Li13 DIQMTQSPATLSLSPGERATLSCRASQSVSSYLAWYQQKPGQAPRLLYDAS 373 NRATGIPARFSGSGSGTDFTLTISSLEPEDFAVYYCQQRSNWPMYTFGQGTK LEIK Li32 DIQMTQSPDSLSASVGDRVITTCQASQDISYYLNWYQQKPGMAPKLLlYDA 377 FILEGGAPSRFSGSGSGTDFSFTISNLQPEDIATYFCQQSDQLPVTFGQGTKVE IR Li33 DIQMTQSPGTLSLSPGERATLSCRASQSVSSYLAWYQQKPGQAPRLLlYDAS 381 NRATGIPARFSGSGSGTEFTLTISSLQSEDFAVYYCQQYDKWPLTFGGGTKV EIK Li34 DIQMTQSPSSLSASVGDRVTITCHASQDISNYLSWYQQKPGKAPKLLIYDAF 385 NLETGVPSRFSGSGSGTDFTFTISSLQPEDFATYYCQHYDNLPFTFGPGTRVA IR I [0199] In a further embodiment, the present invention includes an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid encoding a VL at least 80%, 85%, 90% or 95% identical to a reference VL polypeptide sequence selected from the group consisting of SEQ ID NOs: 273 to 286, 373, 377, 381 and 385,. In certain embodiments, an antibody or antigen binding fragment comprising the VL encoded by the polynucleotide specifically or preferentially binds to Sp35. [02001 In another aspect, the present invention includes an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid sequence encoding a VL of the invention, selected from the group consisting of SEQ ID NOs: 273 to 286, 373, 377, 381 and 385. In certain embodiments, an antibody or antigen-binding fragment comprising the VL encoded by the polynucleotide specifically or preferentially binds to Sp35. [0201] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VL encoded by one or more of the polynucleotides described above specifically or preferentially binds to the same epitope as a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3P1D10.2C3, 3P1E11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (Li02), 35-E04 (Li03), 36-C09 (LiO4), 30-Al1 (LiOS), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (LiO8), 36-A12 (Li09), 28-D02 (LilO), 30-BO1 (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (L1a.13), or will competitively inhibit such a monoclonal antibody from binding to Sp35. [0202] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VL encoded by one or more of the polynucleotides -64 described above specifically or preferentially binds to an Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no greater than 5 x 10-2 M, 10-2 M, 5 x 10 3 M, 10- 3 M, 5 x 10-4M, 10 M, 5 x 10~ 5 M, 10' M, 5 x 10~ 6 M, 10- 6 M, 5 x 10-7 M, 10~ M, 5 x 10~8 M, 10~ M, 5 x 10~'M, 10-9 M, 5 x 1010 M, 10-'0 M, 5 x 10-" M, 10~" M, 5 x 10~ 12 M, 10-12 M, 5 x 10-4 M, 10-~ M, 5 x 10-14 M, 10-4 M, 5 x 10-' M, or 10-5 M. [0203] In additional embodiments, the present invention includes an isolated polynucleotide which encodes a light chain variable region (VL), where the polynucleotide comprises a VL nucleic acid sequence selected from the group consisting of SEQ ID NOs 185 to 194, 371, 375, 379 and 383, as shown in Table 9. In certain embodiments, an antibody or antigen-binding fragment comprising the VL encoded by the polynucleotide specifically or preferentially binds to Sp35. TABLE 9 - VL Polynucleotide Sequences VL Sequence SEQ IDNO: Li02 TTCTATTCTCACAGTGCACAGTACGAATTGACTCAGCCACCCTCAGTGTCCGTGTC 185 CCCAGGACAGACAGCCAGCATCACCTGCTCTGGAGATAAATTGGGGGATAAATTTG CTTCCTGGTATCAGCAGAAGGCAGGCCAGTCCCCTGTGCTGGTCATCTTTCAAGAT AGGAAGCGTCTCTCAGGGATCCCTGAGCGATTCTCTGGCTCCAACTCTGGGAACAC AGCCACTCTGACCATCAGCGGGACCCAGGCTATGGATGAGGCTGACTATTACTGTC AGGCGTGGGACACCAACACTGTGGTCTTCGGCGGAGGGACCAAGCTGACCGTCCTA GGTCAGCCCAAGGCTGCCCCC Li09 TTCTATTCTCACAGTGCACAAGACATCCAGATGACCCAGTCTCCATCCTCCCTGTC 186 TGCATTTGTGGGAGACAGAGTCGCCATCACTTGCCGCGCAAGTCAGAGCATCGACA CCTATTTAAATTGGTATCAGCAGAAACCAGGGAAAGCCCCTAAACTCCTGATCTAT GCTGCATCCAAGTTGGAAGACGGGGTCCCATCAAGATTCAGTGGCAGTGGAACTGG GACAGATTTCACTCTCACCATCAGAAGTCTGCAACCTGAAGATTTTGGAACTTACT ACTGTCAACAGAGTTACAGTCCCCCTCTCACTTTCGGCGGAGGGACCAAGGTGGAG ATCAAACGAACTGTGGCTGCACCA Li06 TTCTATTCTCACAGTGCACAAGACATCCAGATGACCCAGTCTCCTTCCACCCTGTC 187 TGCATCTGTAGGAGACAGAGTCACCATCACTTGCCGGGCCAGTCAGAGTATTAGTA GCTGGTTGGCCTGGTATCAGCAGAAACCAGGGAAAGCCCCTAACCTCCTGATCTAT GCTGCATCCAGTTTACGAACTGGGGTCCCATCAAGATTCAGGGGCAGTGGATCTGG CACAGATTTCACTCTCACCATCAGCAGCCTGCAGCCTGAAGATTTTGCAACGTATT ACTGTCTACAAGATTACAGTTACCCTCTCACTTTTGGCCAGGGGACCAAGCTGGAG ATCAAACGAACTGTGGCTGCACCA Li05 TTCTATTCTCACAGTGCACAGAGCGTCTTGACTCAGCCACCCTCGGTGTCAGTGGC 188 CCCAGGCCAGACGGCCAGGATTTCCTGTGGGGGAGACAACATTGGAAGTAAGAGTG TCCACTGGTACCAGCAGAGGCCAGGCCAGGCCCCTGTCCTGGTCGTGTATGATGAT TATGACCGGCCCTCAGGGATCCCTGAGCGATTCTCTGGCTCCAACTCTGGGGACAC GGCCATCCTGACCATCACCAGGGTCGAAGTCGGGGATGAGGCCGACTTTTATTGTC AGGTGAGGGACAGCCGTACTGAGGAACGGGTGTTCGGCGGAGGGACCAAGGTGACC

GTCTTAGGTCAGCCCAAGGCTGCCCCC

-65 VL Sequence SEQ ID NO:' LiO8 TTCTATTCACAGTGCACAGACTCC GTGACCCAGTCTCCATCTTCCCTGTC 189 TGACGAGGCGGCCACATGCGCATAGCTAT

ATTAAACGAACTGTGGCTGCAC

Lili TTCTATTCTACAGTGCACAGACATCAGTGACCCGTCTCCATCTTCGTG-TC 190 T~-CTTGAAAATACT-ATGCGCATAGGTGC ACTACTTAGCCTGGTATAGCAGACCAGGGJAGCCCCTAGCTCCTGATCTAT GATACATACACTTTGCAGACTGACGTCCCACCGAGGTTCAGCGGCAGTGGTTCGGG GACAGATTTCACTCTCACTATCAGAGCCTGCAGCCTGAAGATACTGCAACTTACT TTTGTCAACAGGCTGACTTTTCCCGCTCTCTTTCGGCGGAGGGACCAGTGGAG ATCAAACGAACTGTGGCTGCC LOTTCTATTCTCACAGTGAAGACATCCGATGACCCAGTCTCCTCTTCCTGT'c 19 ACTGGTTAGCCTGGTATAGCAGACCAGGGAAGCCCCACTCTCCTGATCTAT GCGACATTGAGGGTCCTAGTCCGCGGCGT CTTGAAATCCCCCACACACGACTAGTTGA CTTACTATTGTCAACAGGCTAGACTTTCCCGCTACCTTCGGCGGAGGACr-GG GTGGACCTCAAGCGAAkCTGTGGCTGCACCA LiO 1 TTCTATTCTCACAGTGCA GCTCCAGATGACCCAGTCTCACCTCCCT GTC 192 TGCATCTGTAGGAGAcAGAGTCTCACTTGCGCGAGTAGACATTAGCA ACATAATGACG-GACAGAACCTACCTACA GAGACATTGACGGTCCTAGTCGGCGGACG GAAATCCCCCACG-GCTCACTAGTTGACTC ATTGTCAACAGGCTGACAGGTTCCCTGCGGTCACTTTCGGCGGAGGGACCAAGGTG GAGATCAAACGAACTGTGGCTGCACCA LiO-7 "TTTCCCGG.CGGGATGCCGCCCCGGCGGT 193 CCAGCGCACACACCTCTTGGTATGGGCACT TGGCTTGGTATCACAGAAGCCGGCC-GTCCCCTGTGCTGGTCTCTATCTAGAC ATTAAGAGGCCCGCAGGGATTTCTGCGATTCTCTCTC CTCTATAC AGCCACTCTGACCATCAGAGGCCGCTATGATGAGCTGCTATTACTGTC AGCTGAACAAGTTCGCGGGCAGTACTCGG CAGCCCAAGGCTGCCCCC Li3TTCTATTCTCACAGTGCACACaATCAGATGACCCAGTCTCCTCCTCCCTGTC 194 TGACGAGGCGGCCACATGCGCATAACTAC GCATAATGACGAAACAGAACCTACCTACA GCGACATTCAGGGTCCTAGTCGGCGGACG GAAATCCCCCACGATCGACTAGTTGACTC ACGCAAATAATCCGGGCTCGCAGACAGGA ___ATCAAACGAACTGTGGCTGCC Li1 3 GACATCCAGATGACC TCAGCCCCCCTGTCTTTGTCTGGAAGG 371 CCCCCCTCGGCGCGGGTGACATACTGAC ACGACTGCGCCCGCCTACAGTCTCAAGC ACGCTCGCGTCGGCATGTTGAAATCCCC CCATCAGCAGCCTAGAGCCTGAGATTTTGAGTTTATTACTGTr-GC-GCGTAG dACGCGTTCCTTGCGGACACGAACA -66 VL Sequence SEQ IDNO: Li32 GACATCCAGATGACCCAGTCTCCAGACTCCCTGTCTGCATCTGTTGGAGACAGAG 375 TCACCATCACTTGCCAGGCGAGTCAAGACATTAGCTACTATTTAAATTGGTATCA GCAGAAACCAGGGATGGCCCCTAAACTCCTCATCTACGATGCCTTCATTTTGGAA GGAGGGGCCCCATCACGGTTCAGTGGGAGCGGCTCTGGGACAGATTTTTCTTTCA CCATCAGCAATCTACAGCCTGAGGATATTGCAACTTATTTCTGTCAACAGTCTGA TCAACTGCCCGTGACCTTCGGCCAAGGGACCAAGGTGGAAATCAGA Li33 GACATCCAGATGACCCAGTCTCCAGGCACCCTGTCTTTGTCTCCAGGGGAAAGAG 379 CCACCCTCTCCTGCAGGGCCAGTCAGAGTGTTAGCAGCTACTTAGCCTGGTACCA ACAGAAACCTGGCCAGGCTCCCAGGCTCCTCATCTATGATGCATCCAACAGGGCC ACTGGCATCCCAGCCAGGTTCAGTGGCAGTGGGTCTGGGACAGAGTTCACTCTCA CCATCAGCAGCCTGCAGTCTGAGGATTTTGCAGTTTATTACTGTCAGCAGTATGA TAAGTGGCCGCTCACTTTCGGCGGAGGGACCAAGGTGGAGATCAAA Li34 GACATCCAGATGACCCAGTCTCCATCCTCCCTGTCTGCATCTGTAGGAGACAGAG 383 TCACCATCACTTGCCATGCGAGTCAGGACATTAGCAACTATTTAAGTTGGTATCA GCAGAAACCAGGTAAAGCCCCTAAACTCCTGATCTACGATGCTTTCAATTTGGAG ACAGGAGTCCCATCGAGGTTCAGTGGAAGTGGATCTGGCACAGATTTTACATTCA CCATCAGCAGCCTGCAGCCTGAAGATTTTGCAACATATTACTGTCAGCACTATGA TAATCTCCCATTCACTTTCGGCCCTGGGACCAGAGTGGCGATCAGA [02041 In a further embodiment, the present invention includes an isolated polynucleotide comprising, consisting essentially of, or consisting of a nucleic acid encoding a VL at least 80%, 85%, 90%, or 95% identical to a VL polynucleotide selected from the group consisting of SEQ ID NOs: 185 194, 371, 375, 379 and 383 of Table 9. In certain embodiments, the polynucleotide encodes a VL polypeptide which specifically or preferentially binds to Sp35. [02051 In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VL encoded by one or more of the polynucleotides described above specifically or preferentially binds to the same epitope as a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3PlD1O.2C3, 3P1E11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (LiO2), 35-E04 (Li03), 36-C09 (LiO4), 30-All (LiO5), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (LiO8), 36-A12 (Li09), 28-D02 (LilO), 30-B01 (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13), or will competitively inhibit such a monoclonal antibody from binding to Sp35. [0206] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a VL encoded by one or more of the polynucleotides described above specifically or preferentially binds to an Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no greater than 5 x 10- M, 10- M, 5 x 103 M, 10- M, 5 x 104 M, 1 0 - M, 5 x 10~ M, 104 M, 5 x 10- M, 10- M, 5 x -67 107 M, 104 M, 5 x 10~8 M, 10' M, 5 x 109 M, 10-9 M, 5 x 10~1" M, 1010 M, 5 x 10-1 M, 10-u M, 5 x 10 l M, 1012 M, 5 x 10-" M, 10- M, 5 x 10~" M, 1014 M, 5 x 10^5 M, or 10-15 M. [02071 Any of the polynucleotides described above may further include additional nucleic acids, encoding, e.g., a signal peptide to direct secretion of the encoded polypeptide, antibody constant regions as described herein, or other heterologous polypeptides as described herein. [0208] Also, as described in more detail elsewhere herein, the present invention includes compositions comprising the polynucleotides comprising one or more of the polynucleotides described above. In one embodiment, the invention includes compositions comprising a first polynucleotide and second polynucleotide wherein said first polynucleotide encodes a VH polypeptide as described herein and wherein said second polynucleotide encodes a VL polypeptide as described herein. Specifically a composition which comprises, consists essentially of, or consists of a VH polynucleotide, as show in Table 7, and a VL polynucleotide, as shown in Table 9, wherein said VH polynucleotide and said VL polynucleotide are selected from the group consisting of i) SEQ ID NO:173 and SEQ ID NO:185; ii) SEQ ID NO:174 and SEQ ID NO:186; iii) SEQ ID NO:175 and SEQ ID NO:187; iv) SEQ ID NO:176 and SEQ ID NO:188; v) SEQ ID NO:178 and SEQ ID NO:189; vi) SEQ ID NO:179 and SEQ ID NO:190; vii) SEQ ID NO:180 and SEQ ID NO:191; viii) SEQ ID NO:181 and SEQ ID NO:192; ix) SEQ ID NO:182 and SEQ ID NO:193; x) SEQ ID NO:183 and SEQ ID NO: 194; xi) SEQ ID NO:370 and SEQ ID NO:371; xii) SEQ ID NO:374 and SEQ ID NO:375; xiii) SEQ ID NO:378 and SEQ ID NO:379; and xiv) SEQ ID NO:382 and SEQ ID NO:385. 102091 The present invention also includes fragments of the polynucleotides of the invention, as described elsewhere. Additionally polynucleotides which encode fusion polynucleotides, Fab fragments, and other derivatives, as described herein, are also contemplated by the invention. [02101 The polynucleotides may be produced or manufactured by any method known in the art. For example, if the nucleotide sequence of the antibody is known, a polynucleotide encoding the antibody may be assembled from chemically synthesized oligonucleotides (e.g., as described in Kutmeier et al., BioTechniques 17:242 (1994)), which, briefly, involves the synthesis of overlapping -68 oligonucleotides containing portions of the sequence encoding the antibody, annealing and ligating of those oligonucleotides, and then amplification of the ligated oligonucleotides by PCR. [0211] Alternatively, a polynucleotide encoding an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof may be generated from nucleic acid from a suitable source. If a clone containing a nucleic acid encoding a particular antibody is not available, but the sequence of the antibody molecule is known, a nucleic acid encoding the antibody may be chemically synthesized or obtained from a suitable source (e.g., an antibody cDNA library, or a cDNA library generated from, or nucleic acid, preferably poly A+RNA, isolated from, any tissue or cells expressing the antibody or other Sp35 antibody, such as hybridoma cells selected to express an antibody) by PCR amplification using synthetic primers hybridizable to the 3' and 5' ends of the sequence or by cloning using an oligonucleotide probe specific for the particular gene sequence to identify, e.g., a cDNA clone from a cDNA library that encodes the antibody or other Sp35 antibody. Amplified nucleic acids generated by PCR may then be cloned into replicable cloning vectors using any method well known in the art. [0212] Once the nucleotide sequence and corresponding amino acid sequence of the Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof is determined, its nucleotide sequence may be manipulated using methods well known in the art for the manipulation of nucleotide sequences, e.g., recombinant DNA techniques, site directed mutagenesis, PCR, etc. (see, for example, the techniques described in Sambrook et al., Molecular Cloning, A Laboratory Manual, 2d Ed., Cold Spring Harbor Laboratory, Cold Spring Harbor, N.Y. (1990) and Ausubel et al., eds., Current Protocols in Molecular Biology, John Wiley & Sons, NY (1998), which are both incorporated by reference herein in their entireties ), to generate antibodies having a different amino acid sequence, for example to create amino acid substitutions, deletions, and/or insertions. [0213] A polynucleotide encoding an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof can be composed of any polyribonucleotide or polydeoxribonucleotide, which may be unmodified RNA or DNA or modified RNA or DNA. For example, a polynucleotide encoding Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof can be composed of single- and double-stranded DNA, DNA that is a mixture of single- and double-stranded regions, single- and double-stranded RNA, and RNA that is mixture of single- and double-stranded regions, hybrid molecules comprising DNA and RNA that may be single-stranded or, more typically, double-stranded or a mixture of single- and double-stranded regions. In addition, a polynucleotide encoding an Sp 3 5 antibody, or antigen-binding fragment, variant, or derivative thereof can be composed of triple-stranded regions comprising RNA or DNA or both RNA and DNA. A polynucleotide encoding an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof may also contain one or more modified bases or DNA or RNA backbones modified for stability or for other reasons. "Modified" bases include, for example, tritylated bases and unusual bases such as inosine. A variety of - 69 modifications can be made to DNA and RNA; thus, "polynucleotide" embraces chemically, enzymatically, or metabolically modified forms. [02141 An isolated polynucleotide encoding a non-natural variant of a polypeptide derived from an immunoglobulin (e.g., an immunoglobulin heavy chain portion or light chain portion) can be created by introducing one or more nucleotide substitutions, additions or deletions into the nucleotide sequence of the immunoglobulin such that one or more amino acid substitutions, additions or deletions are introduced into the encoded protein. Mutations may be introduced by standard techniques, such as site directed mutagenesis and PCR-mediated mutagenesis. Preferably, conservative amino acid substitutions are made at one or more non-essential amino acid residues. V. SP35 ANTIBODYPOLYPEPTIDES [02151 The present invention is further directed to isolated polypeptides which make up Sp35 antibodies, antigen binding fragments, variants or derivatives thereof. Sp35 antibodies of the present invention comprise polypeptides, e.g., amino acid sequences encoding Sp35-specific antigen binding regions derived from immunoglobulin molecules. A polypeptide or amino acid sequence "derived from" a designated protein refers to the origin of the polypeptide. In certain cases, the polypeptide or amino acid sequence which is derived from a particular starting polypeptide or amino acid sequence has an amino acid sequence that is essentially identical to that of the starting sequence, or a portion thereof, wherein the portion consists of at least 10-20 amino acids, at least 20-30 amino acids, at least 30-50 amino acids, or which is otherwise identifiable to one of ordinary skill in the art as having its origin in the starting sequence. [02161 In one embodiment, the present invention provides an isolated polypeptide comprising, consisting essentially of, or consisting of an immunoglobulin heavy chain variable region (VH), where at least one of CDRs of the heavy chain variable region or at least two of the CDRs of the heavy chain variable region are at least 80%, 85%, 90% or 95% identical to reference heavy chain CDR1, CDR2 or CDR3 amino acid sequences from monoclonal Sp35 antibodies disclosed herein. Alternatively, the CDR1, CDR2 and CDR3 regions of the VH are at least 80%, 85%, 90% or 95% identical to reference heavy chain CDR1, CDR2 and CDR3 amino acid sequences from monoclonal Sp35 antibodies disclosed herein. Thus, according to this embodiment a heavy chain variable region of the invention has CDR1, CDR2, and CDR3 polypeptide sequences related to the groups shown in Table 4, supra. In certain embodiments, an antibody or antigen-binding fragment comprising the VH polypeptide specifically or preferentially binds to Sp35. [0217] In another embodiment, the present invention provides an isolated polypeptide comprising, consisting essentially of, or consisting of an immunoglobulin heavy chain variable region (VII) in which the CDR1, CDR2, and CDR3 regions have polypeptide sequences which are identical to the 70 CDR1, CDR2, and CDR3 groups shown in Table 4. In certain embodiments, an antibody or antigen binding fragment comprising the VH polypeptide specifically or preferentially binds to Sp35. [0218] In a further embodiment, the present invention includes an isolated polypeptide comprising, consisting essentially of, or consisting of a VH polypeptide at least 80%, 85%, 90% 95% or 100% identical to a reference VH polypeptide sequence selected from the group consisting of SEQ ID NOs:158 to 172, 372, 376, 380 and 384 as shown in Table 6. In certain embodiments, an antibody or antigen-binding fragment comprising the VH polypeptide specifically or preferentially binds to Sp35. [02191 In another aspect, the present invention includes an isolated polypeptide comprising, consisting essentially of, or consisting of a VH polypeptide selected from the group consisting of SEQ ID NOs: 158 to 172, 372, 376, 380 and 384 as shown in Table 6. In certain embodiments, an antibody or antigen-binding fragment comprising the VH polypeptide specifically or preferentially binds to Sp35. [0220] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a one or more of the VH polypeptides described above specifically or preferentially binds to the same epitope as a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3PlD1O.2C3, 3PlE11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30 C12 (LiOl), 38-DO1 (LiO2), 35-E04 (Li03), 36-C09 (LiO4), 30-All (Li05), 34-F02 (LiO6), 29-E07 (LiO7), 34-G04 (Li08), 36-A12 (LiO9), 28-D02 (LilO), 30-BO (Lil 1), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13), or will competitively inhibit such a monoclonal antibody from binding to Sp35. [0221] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of one or more of the VH polypeptides described above specifically or preferentially binds to an Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no greater than 5 x 10-2 M, 10.2 M, 5 x 104 M, 10-' M, 5 x 104 M, 10-4 M, 5 x 10-5 M, 10-5 M, 5 x 10- M, 10-6 M, 5 x 10-7 M, l0 M, 5 x 10-8 M, 10-' M, 5 x 10- M, 10- M, 5 x 1014 M, 1010 M, 5 x 10~" M, 10~" M, 5 x 10-12 M, 102 M, 5 x 10-11 M, 1013 M, 5 x 10-14 M, 1014 M, 5 x 1015 M, or 10-15 M. 102221 In another embodiment, the present invention provides an isolated polypeptide comprising, consisting essentially of, or consisting of an immunoglobulin light chain variable region (VL), where at least one of the CDRs of the light chain variable region or at least two of the CDRs of the light chain variable region are at least 80%, 85%, 90% or 95% identical to reference heavy chain CDR1, CDR2, or CDR3 amino acid sequences from monoclonal Sp35 antibodies disclosed herein. Alternatively, the CDR1, CDR2 and CDR3 regions of the VL are at least 80%, 85%, 90% or 95% identical to reference -71 light chain CDRI, CDR2, and CDR3 amino acid sequences from monoclonal Sp35 antibodies disclosed herein. Thus, according to this embodiment a light chain variable region of the invention has CDR1, CDR2, and CDR3 polypeptide sequences related to the polypeptides shown in Table 5, supra. In certain embodiments, an antibody or antigen-binding fragment comprising the VL polypeptide specifically or preferentially binds to Sp35. [02231 In another embodiment, the present invention provides an isolated polypeptide comprising, consisting essentially of, or consisting of an immunoglobulin light chain variable region (VL) in which the CDR1, CDR2, and CDR3 regions have polypeptide sequences which are identical to the CDR1, CDR2, and CDR3 groups shown in Table 5. In certain embodiments, an antibody or antigen-binding fragment comprising the VL polypeptide specifically or preferentially binds to Sp35. 102241 In a further embodiment, the present invention includes an isolated polypeptide comprising, consisting essentially of, or consisting of a VL polypeptide at least 80%, 85%, 90% or 95% identical to a reference VL polypeptide sequence selected from the group consisting of SEQ ID NOs:273 to 286, 373, 377, 381 and 385, shown in Table 8. In certain embodiments, an antibody or antigen-binding fragment comprising the VL polypeptide specifically or preferentially binds to Sp35. 102251 In another aspect, the present invention includes an isolated polypeptide comprising, consisting essentially of, or consisting of a VL polypeptide selected from the group consisting of SEQ ID NOs: 273 to 286, 373, 377, 381 and 385,shown in Table 8. In certain embodiments, an antibody or antigen-binding fragment comprising the VL polypeptide specifically or preferentially binds to Sp35. 10226] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, one or more of the VL polypeptides described above specifically or preferentially binds to the same epitope as a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3P1DIO.2C3, 3PIE11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A12B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (LiO2), 35-E04 (Li03), 36-C09 (LiO4), 30-Al1 (Li05), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (LiO8), 36-A12 (LiO9), 28-D02 (LilO), 30-BO (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (LIa.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13), or will competitively inhibit such a monoclonal antibody from binding to Sp35. [0227] In certain embodiments, an antibody or antigen-binding fragment thereof comprising, consisting essentially of, or consisting of a one or more of the VL polypeptides described above specifically or preferentially binds to an Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no greater than 5 x le 2 M, 102 M, 5 x 10-3 M, 10-3 M, 5 x 10 4 M, 10 4 M, 5 x 10~ M, 10- M, 5 x 10- M, 106 M, 5 x 10- M, 10- - 72 M, 5 x 10~8 M, 10- M, 5 x 10-9 M, 109 M, 5 x 101* M, 10" M, 5 x 10-" M, 10-11 M, 5 x 1012 M, 1012 M, 5 x 1013 M, 10~3 M, 5 x 10-4 M, 10-" M, 5 x 10-15 M, or 10-4 M. [02281 In other embodiments, an antibody or antigen-binding fragment thereof comprises, consists essentially of or consists of a VH polypeptide, as shown in Table 6, and a VL polypeptide, as shown in Table 8 , selected from the group consisting of: i) SEQ ID NO:170 and SEQ ID NO:283; ii) SEQ ID NO:171 and SEQ ID NO:284; iii) SEQ ID NO:172 and SEQ ID NO:285; iv) SEQ ID NO:172 and SEQ ID NO:286; v) SEQ ID NO: 158 and SEQ ID NO:273; vi) SEQ ID NO:159 and SEQ ID NO:274; vii) SEQ ID NO:160 and SEQ ID NO:275; viii) SEQ ID NO:161 and SEQ ID NO:276; ix) SEQ ID NO:163 and SEQ ID NO:277; x) SEQ ID NO:164 and SEQ ID NO:278; xi) SEQ ID NO: 165 and SEQ ID NO:279; xii) SEQ ID NO: 166 and SEQ ID NO:280; xiii) SEQ ID NO:167 and SEQ ID NO:281; xiv) SEQ ID NO:168 and SEQ ID NO:282; xv) SEQ ID NO:372 and SEQ ID NO:373; xvi) SEQ ID NO:376 and SEQ ID NO:377; xvii) SEQ ID NO:380 and SEQ ID NO:381; and xviii) SEQ ID NO:384 and SEQ ID NO:385. [02291 Any of the polypeptides described above may further include additional polypeptides, e.g., a signal peptide to direct secretion of the encoded polypeptide, antibody constant regions as described herein, or other heterologous polypeptides as described herein. Additionally, polypeptides of the invention include polypeptide fragments as described elsewhere. Additionally polypeptides of the invention include fusion polypeptide, Fab fragments, and other derivatives, as described herein. [02301 Also, as described in more detail elsewhere herein, the present invention includes compositions comprising the polypeptides described above. [02311 It will also be understood by one of ordinary skill in the art that Sp 3 5 antibody polypeptides as disclosed herein may be modified such that they vary in amino acid sequence from the naturally occurring binding polypeptide from which they were derived. For example, a polypeptide or amino acid sequence derived from a designated protein may be similar, e.g., have a certain percent identity to -73 the starting sequence, e.g., it may be 60%, 70%, 75%, 80%, 85%, 90%, or 95% identical to the starting sequence. [0232] Furthermore, nucleotide or amino acid substitutions, deletions, or insertions leading to conservative substitutions or changes at "non-essential" amino acid regions may be made. For example, a polypeptide or amino acid sequence derived from a designated protein may be identical to the starting sequence except for one or more individual amino acid substitutions, insertions, or deletions, e.g., one, two, three, four, five, six, seven, eight, nine, ten, fifteen, twenty or more individual amino acid substitutions, insertions, or deletions. In certain embodiments, a polypeptide or amino acid sequence derived from a designated protein has one to five, one to ten, one to fifteen, or one to twenty individual amino acid substitutions, insertions, or deletions relative to the starting sequence. [0233] Certain Sp35 antibody polypeptides of the present invention comprise, consist essentially of, or consist of an amino acid sequence derived from a human amino acid sequence. However, certain Sp35 antibody polypeptides comprise one or more contiguous amino acids derived from another mammalian species. For example, an Sp35 antibody of the present invention may include a primate heavy chain portion, hinge portion, or antigen binding region. In another example, one or more murine derived amino acids may be present in a non-murine antibody polypeptide, e.g., in an antigen binding site of an Sp35 antibody. In certain therapeutic applications, Sp35-specific antibodies, or antigen binding fragments, variants, or analogs thereof are designed so as to not be immunogenic in the animal to which the antibody is administered. [0234] In certain embodiments, an Sp35 antibody polypeptide comprises an amino acid sequence or one or more moieties not normally associated with an antibody. Exemplary modifications are described in more detail below. For example, a single-chain fv antibody fragment of the invention may comprise a flexible linker sequence, or may be modified to add a functional moiety (e.g., PEG, a drug, a toxin, or a label). [0235] An Sp35 antibody polypeptide of the invention may comprise, consist essentially of, or consist of a fusion protein. Fusion proteins are chimeric molecules which comprise, for example, an immunoglobulin antigen-binding domain with at least one target binding site, and at least one heterologous portion, i.e., a portion with which it is not naturally linked in nature. The amino acid sequences may normally exist in separate proteins that are brought together in the fusion polypeptide or they may normally exist in the same protein but are placed in a new arrangement in the fusion polypeptide. Fusion proteins may be created, for example, by chemical synthesis, or by creating and translating a polynucleotide in which the peptide regions are encoded in the desired relationship. [0236] The term "heterologous" as applied to a polynucleotide or a polypeptide, means that the polynucleotide or polypeptide is derived from a distinct entity from that of the rest of the entity to which it is being compared. For instance, as used herein, a "heterologous polypeptide" to be fused to an -74 Sp35 antibody, or an antigen-binding fragment, variant, or analog thereof is derived from a non immunoglobulin polypeptide of the same species, or an immunoglobulin or non-immunoglobulin polypeptide of a different species. [0237] A "conservative amino acid substitution" is one in which the amino acid residue is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art, including basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, seine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Thus, a nonessential amino acid residue in an immunoglobulin polypeptide is preferably replaced with another amino acid residue from the same side chain family. In another embodiment, a string of amino acids can be replaced with a structurally similar string that differs in order and/or composition of side chain family members. [0238] Alternatively, in another embodiment, mutations may be introduced randomly along all or part of the immunoglobulin coding sequence, such as by saturation mutagenesis, and the resultant mutants can be incorporated into Sp35 antibodies for use in the diagnostic and treatment methods disclosed herein and screened for their ability to bind to the desired antigen, e.g., Sp35. VI. FUSION PROTEINS AND ANTIBODY CONJUGATES [0239] As discussed in more detail elsewhere herein, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention may further be recombinantly fused to a heterologous polypeptide at the N- or C-terminus or chemically conjugated (including covalent and non-covalent conjugations) to polypeptides or other compositions. For example, Sp35-specific Sp35 antibodies may be recombinantly fused or conjugated to molecules useful as labels in detection assays and effector molecules such as heterologous polypeptides, drugs, radionuclides, or toxins. See, e.g., PCT publications WO 92/08495; WO 91/14438; WO 89/12624; U.S. Patent No. 5,314,995; and EP 396,387, which are incorporated herein by reference in their entireties. 102401 Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention include derivatives that are modified, i.e., by the covalent attachment of any type of molecule to the antibody such that covalent attachment does not prevent the antibody binding Sp35. For example, but not by way of limitation, the antibody derivatives include antibodies that have been modified, e.g., by glycosylation, acetylation, pegylation, phosphylation, phosphorylation, amidation, derivatization by known protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein, etc. Any of numerous chemical modifications may be carried out by known techniques, including, but -75 not limited to specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. Additionally, the derivative may contain one or more non-classical amino acids. [02411 Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be composed of amino acids joined to each other by peptide bonds or modified peptide bonds, i.e., peptide isosteres, and may contain amino acids other than the 20 gene-encoded amino acids. Sp35-specfic antibodies may be modified by natural processes, such as posttranslational processing, or by chemical modification techniques which are well known in the art. Such modifications are well described in basic texts and in more detailed monographs, as well as in a voluminous research literature. Modifications can occur anywhere in the Sp35-specific antibody, including the peptide backbone, the amino acid side-chains and the amino or carboxyl termini, or on moieties such as carbohydrates. It will be appreciated that the same type of modification may be present in the same or varying degrees at several sites in a given Sp35-specific antibody. Also, a given Sp35-specific antibody may contain many types of modifications. Sp35-specific antibodies may be branched, for example, as a result of ubiquitination, and they may be cyclic, with or without branching. Cyclic, branched, and branched cyclic Sp35-specific antibodies may result from posttranslation natural processes or may be made by synthetic methods. Modifications include acetylation, acylation, ADP-ribosylation, amidation, covalent attachment of flavin, covalent attachment of a heme moiety, covalent attachment of a nucleotide or nucleotide derivative, covalent attachment of a lipid or lipid derivative, covalent attachment of phosphotidylinositol, cross-linking, cyclization, disulfide bond formation, demethylation, formation of covalent cross-links, formation of cysteine, formation of pyroglutamate, formylation, gamma-carboxylation, glycosylation, GPI anchor formation, hydroxylation, iodination, methylation, myristoylation, oxidation, pegylation, proteolytic processing, phosphorylation, prenylation, racemization, selenoylation, sulfation, transfer-RNA mediated addition of amino acids to proteins such as arginylation, and ubiquitination. (See, for instance, Proteins - Structure And Molecular Properties, T. E. Creighton, W. H. Freeman and Company, New York 2nd Ed., (1993); Posttranslational Covalent Modification OfProteins, B. C. Johnson, Ed., Academic Press, New York, pgs. 1-12 (1983); Seifter et al., Meth Enzymol 182:626-646 (1990); Rattan et al., Ann NYAcad Sci 663:48-62 (1992)). [02421 The present invention also provides for fusion proteins comprising an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof, and a heterologous polypeptide. The heterologous polypeptide to which the antibody is fused may be useful for function or is useful to target the Sp35 polypeptide expressing cells. In one embodiment, a fusion protein of the invention comprises, consists essentially of, or consists of, a polypeptide having the amino acid sequence of any one or more of the VH regions of an antibody of the invention or the amino acid sequence of any one or more of the VL regions of an antibody of the invention or fragments or variants thereof, and a heterologous polypeptide sequence. In another embodiment, a fusion protein for use in the diagnostic and treatment -76 methods disclosed herein comprises, consists essentially of, or consists of a polypeptide having the amino acid sequence of any one, two, three of the VH CDRs of an Sp35-specific antibody, or fragments, variants, or derivatives thereof, or the amino acid sequence of any one, two, three of the VL CDRs of an Sp35-specific antibody, or fragments, variants, or derivatives thereof, and a heterologous polypeptide sequence. In one embodiment, the fusion protein comprises a polypeptide having the amino acid sequence of a VH CDR3 of an Sp35-specific antibody of the present invention, or fragment, derivative, or variant thereof, and a heterologous polypeptide sequence, which fusion protein specifically binds to at least one epitope of Sp35. In another embodiment, a fusion protein comprises a polypeptide having the amino acid sequence of at least one VH region of an Sp35-specific antibody of the invention and the amino acid sequence of at least one VL region of an Sp35-specific antibody of the invention or fragments, derivatives or variants thereof, and a heterologous polypeptide sequence. Preferably, the VH and VL regions of the fusion protein correspond to a single source antibody (or scFv or Fab fragment) which specifically binds at least one epitope of Sp35. In yet another embodiment, a fusion protein for use in the diagnostic and treatment methods disclosed herein comprises a polypeptide having the amino acid sequence of any one, two, three or more of the VH CDRs of an Sp35-specific antibody and the amino acid sequence of any one, two, three or more of the VL CDRs of an Sp35-specific antibody, or fragments or variants thereof, and a heterologous polypeptide sequence. Preferably, two, three, four, five, six, or more of the VHCDR(s) or VLCDR(s) correspond to single source antibody (or scFv or Fab fragment) of the invention. Nucleic acid molecules encoding these fusion proteins are also encompassed by the invention. [02431 Exemplary fusion proteins reported in the literature include fusions of the T cell receptor (Gascoigne et al., Proc. Natl. Acad. Sci. USA 84:2936-2940 (1987)); CD4 (Capon et al., Nature 337:525-531 (1989); Traunecker et al., Nature 339:68-70 (1989); Zettmeissl et al., DNA Cell Biol. USA 9:347-353 (1990); and Byrn et al., Nature 344:667-670 (1990)); L-selectin (homing receptor) (Watson et al., J. Cell. Biol. 110:2221-2229 (1990); and Watson et al., Nature 349:164-167 (1991)); CD44 (Aruffo et al., Cell 61:1303-1313 (1990)); CD28 and B7 (Linsley et al., J. Exp. Med. 173:721-730 (1991)); CTLA-4 (Lisley et al., J. Exp. Med. 174:561-569 (1991)); CD22 (Stamenkovic et al., Cell 66:1133-1144 (1991)); TNF receptor (Ashkenazi et al., Proc. Nat. Acad. Sci. USA 88:10535-10539 (1991); Lesslauer et al., Eur. J. Immunol. 27:2883-2886 (1991); and Peppel et al., J. Exp. Med. 174:1483-1489 (1991)); and IgE receptor a (Ridgway and Gorman, J. Cell. Biol. Vol. 115, Abstract No. 1448 (1991)). [0244] In certain embodiments, Sp35 antibodies, antibody fragments, derivatives and variants thereof further comprise a targeting moiety. Targeting moieties include a protein or a peptide which directs localization to a certain part of the body, for example, to the brain or compartments therein. In certain embodiments, Sp35 antibodies, antibody fragments, derivatives and variants thereof are attached or fused to a brain targeting moiety. The brain targeting moieties are attached -77 covalently (e.g., direct, translational fusion, or by chemical linkage either directly or through a spacer molecule, which can be optionally cleavable) or non-covalently attached (e.g., through reversible interactions such as avidin, biotin, protein A, IgG, etc.). In other embodiments, the Sp35 antibodies, antibody fragments, derivatives and variants thereof are attached to one more brain targeting moieties. In additional embodiments, the brain targeting moiety is attached to a plurality of Sp35 antibodies, antibody fragments, derivatives and variants thereof. [0245] A brain targeting moiety associated with an Sp35 antibody, antibody fragment, derivative or variant thereof enhances brain delivery of such an Sp35 antibodies, antibody fragments, dervatives and variants thereof. A number of polypeptides have been described which, when fused to a protein or therapeutic agent, delivers the protein or therapeutic agent through the blood brain barrier (BBB). Non-limiting examples include the single domain antibody FC5 (Abulrob et al. (2005) J. Neurochen. 95, 1201-1214); mAB 83-14, a monoclonal antibody to the human insulin receptor (Pardridge et al. (1995) Pharmacol. Res. 12, 807-816); the B2, B6 and B8 peptides binding to the human transferrin receptor (hTfR) (Xia et al. (2000) J. Virol. 74, 11359 11366); the OX26 monoclonal antibody to the transferrin receptor (Pardridge et al. (1991) J. Pharmacol. Exp. Other. 259, 66-70); and SEQ ID NOs: 1-18 of U.S. Patent No. 6,306,365. The contents of the above references are incorporated herein by reference in their entirety. [02461 Enhanced brain delivery of an Sp35 antibody, antibody fragment, derivative or variant thereof is determined by a number of means well established in the art. For example, administering to an animal a radioactively, enzymatically or fluorescently labeled Sp35 antibody, antibody fragment, derivative and variant thereof linked to a brain targeting moiety; determining brain localization; and comparing localization with an equivalent radioactively, enzymatically or fluorescently labeled Sp35 antibody, antibody fragment, deirvative or variant thereof that is not associated with a brain targeting moiety. Other means of determining enhanced targeting are described in the above references. [0247] As discussed elsewhere herein, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention may be fused to heterologous polypeptides to increase the in vivo half life of the polypeptides or for use in immunoassays using methods known in the art. For example, in one embodiment, PEG can be conjugated to the Sp35 antibodies of the invention to increase their half-life in vivo. Leong, S.R., et al., Cytokine 16:106 (2001); Adv. in Drug Deliv. Rev. 54:531 (2002); or Weir et al., Biochein. Soc. Transactions 30:512 (2002). [0248] Moreover, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be fused to marker sequences, such as a peptide to facilitate their purification or detection. In preferred embodiments, the marker amino acid sequence is a hexa-histidine peptide, such as the tag provided in a pQE vector (QIAGEN, Inc., 9259 Eton Avenue, Chatsworth, Calif., 91311), -78 among others, many of which are commercially available. As described in Gentz et al., Proc. Nati. Acad. Sci. USA 86:821-824 (1989), for instance, hexa-histidine provides for convenient purification of the fusion protein. Other peptide tags useful for purification include, but are not limited to, the "HA" tag, which corresponds to an epitope derived from the influenza hemagglutinin protein (Wilson et al., Cell 37:767 (1984)) and the "flag" tag. [0249] Fusion proteins can be prepared using methods that are well known in the art (see for example US Patent Nos. 5,116,964 and 5,225,538). The precise site at which the fusion is made may be selected empirically to optimize the secretion or binding characteristics of the fusion protein. DNA encoding the fusion protein is then transfected into a host cell for expression. [02501 Sp35 antibodies or antigen-binding fragments, variants, or derivatives thereof of the present invention may be used in non-conjugated form or may be conjugated to at least one of a variety of molecules, e.g., to improve the therapeutic properties of the molecule, to facilitate target detection, or for imaging or therapy of the patient. Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be labeled or conjugated either before or after purification, when purification is performed. [02511 In particular, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention may be conjugated to therapeutic agents, prodrugs, peptides, proteins, enzymes, viruses, lipids, biological response modifiers, pharmaceutical agents, or PEG. [02521 Those skilled in the art will appreciate that conjugates may also be assembled using a variety of techniques depending on the selected agent to be conjugated. For example, conjugates with biotin are prepared e.g. by reacting a binding polypeptide with an activated ester of biotin such as the biotin N-hydroxysuccinimide ester. Similarly, conjugates with a fluorescent marker may be prepared in the presence of a coupling agent, e.g. those listed herein, or by reaction with an isothiocyanate, preferably fluorescein-isothiocyanate. Conjugates of the Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention are prepared in an analogous manner. [0253] The present invention further encompasses Sp 3 5 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention conjugated to a diagnostic or therapeutic agent. The Sp35 antibodies can be used diagnostically to, for example, monitor the development or progression of a neurological disease as part of a clinical testing procedure to, e.g., determine the efficacy of a given treatment and/or prevention regimen. Detection can be facilitated by coupling the Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof to a detectable substance. Examples of detectable substances include various enzymes, prosthetic groups, fluorescent materials, luminescent materials, bioluminescent materials, radioactive materials, positron emitting metals using various positron emission tomographies, and nonradioactive paramagnetic metal ions. See, for example, U.S. Pat. No. 4,741,900 for metal ions which can be conjugated to antibodies for use as diagnostics -79 according to the present invention. Examples of suitable enzymes include horseradish peroxidase, alkaline phosphatase, p-galactosidase, or acetylcholinesterase; examples of suitable prosthetic group complexes include streptavidin/biotin and avidin/biotin; examples of suitable fluorescent materials include umbelliferone, fluorescein, fluorescein isothiocyanate, rhodamine, dichlorotriazinylamine fluorescein, dansyl chloride or phycoerythrin; an example of a luminescent material includes luminol; examples of bioluminescent materials include luciferase, luciferin, and aequorin; and examples of suitable radioactive material include 125 131 IIn or 99 Tc. [02541 An Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof also can be detectably labeled by coupling it to a chemiluminescent compound. The presence of the chemiluminescent-tagged Sp35 antibody is then determined by detecting the presence of luminescence that arises during the course of a chemical reaction. Examples of particularly useful chemiluminescent labeling compounds are luminol, isoluminol, theromatic acridinium ester, imidazole, acridinium salt and oxalate ester. [0255] One of the ways in which an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof can be detectably labeled is by linking the same to an enzyme and using the linked product in an enzyme immunoassay (EIA) (Voller, A., "The Enzyme Linked Ixnmunosorbent Assay (ELISA)" Microbiological Associates Quarterly Publication, Walkersville, Md., Diagnostic Horizons 2:1-7 (1978)); Voller et al., J. Clin. Pathol. 31:507-520 (1978); Butler, J. E., Meth. Enrymol. 73:482 523 (1981); Maggio, E. (ed.), Enzyme Immunoassay, CRC Press, Boca Raton, Fla., (1980); Ishikawa, E. et al., (eds.), Enzyme Immunoassay, Kgaku Shoin, Tokyo (1981). The enzyme, which is bound to the Sp35 antibody will react with an appropriate substrate, preferably a chromogenic substrate, in such a manner as to produce a chemical moiety which can be detected, for example, by spectrophotometric, fluorimetric or by visual means. Enzymes which can be used to detectably label the antibody include, but are not limited to, malate dehydrogenase, staphylococcal nuclease, delta-5-steroid isomerase, yeast alcohol dehydrogenase, alpha-glycerophosphate, dehydrogenase, triose phosphate isomerase, horseradish peroxidase, alkaline phosphatase, asparaginase, glucose oxidase, beta-galactosidase, ribonuclease, urease, catalase, glucose-6-phosphate dehydrogenase, glucoamylase and acetylcholinesterase. Additionally, the detection can be accomplished by colorimetric methods which employ a chromogenic substrate for the enzyme. Detection may also be accomplished by visual comparison of the extent of enzymatic reaction of a substrate in comparison with similarly prepared standards. [0256] Detection may also be accomplished using any of a variety of other immunoassays. For example, by radioactively labeling the Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof, it is possible to detect the antibody through the use of a radioimmunoassay (RIA) (see, for example, Weintraub, B., Principles of Radioimmunoassays, Seventh Training Course on - 80 Radioligand Assay Techniques, The Endocrine Society, (March, 1986)), which is incorporated by reference herein). The radioactive isotope can be detected by means including, but not limited to, a gamma counter, a scintillation counter, or autoradiography. [0257] An Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof can also be detectably labeled using fluorescence emitting metals such as 152Eu, or others of the lanthanide series. These metals can be attached to the 'antibody using such metal chelating groups as diethylenetriaminepentacetic acid (DTPA) or ethylenediaminetetraacetic acid (EDTA). [0258] Techniques for conjugating various moieties to an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof are well known, see, e.g., Arnon et al., "Monoclonal Antibodies For Immunotargeting Of Drugs In Cancer Therapy", in Monoclonal Antibodies And Cancer Therapy, Reisfeld et al. (eds.), pp. 243-56 (Alan R. Liss, Inc. (1985); Hellstrom et al., "Antibodies For Drug Delivery", in Controlled Drug Delivery (2nd Ed.), Robinson et al. (eds.), Marcel Dekker, Inc., pp. 623 53 (1987); Thorpe, "Antibody Carriers Of Cytotoxic Agents In Cancer Therapy: A Review", in Monoclonal Antibodies '84: Biological And Clinical Applications, Pinchera et al. (eds.), pp. 475-506 (1985); "Analysis, Results, And Future Prospective Of The Therapeutic Use Of Radiolabeled Antibody In Cancer Therapy", in Monoclonal Antibodies For Cancer Detection And Therapy, Baldwin et al. (eds.), Academic Press pp. 303-16 (1985), and Thorpe et al., "The Preparation And Cytotoxic Properties Of Antibody-Toxin Conjugates", Immunol. Rev. 62:119-58 (1982). VII. EXPRESSION OF ANTIBODY POLYPEPTIDES [0259] As is well known, RNA may be isolated from the original hybridoma cells or from other transformed cells by standard techniques, such as guanidinium isothiocyanate extraction and precipitation followed by centrifugation or chromatography. Where desirable, mRNA may be isolated from total RNA by standard techniques such as chromatography on oligo dT cellulose. Suitable techniques are familiar in the art. [02601 In one embodiment, cDNAs that encode the light and the heavy chains of the antibody may be made, either simultaneously or separately, using reverse transcriptase and DNA polymerase in accordance with well known methods. PCR may be initiated by consensus constant region primers or by more specific primers based on the published heavy and light chain DNA and amino acid sequences. As discussed above, PCR also may be used to isolate DNA clones encoding the antibody light and heavy chains. In this case the libraries may be screened by consensus primers or larger homologous probes, such as mouse constant region probes. [02611 DNA, typically plasmid DNA, may be isolated from the cells using techniques known in the art, restriction mapped and sequenced in accordance with standard, well known techniques set forth in detail, e.g., in the foregoing references relating to recombinant DNA techniques. Of course, the DNA -81 may be synthetic according to the present invention at any point during the isolation process or subsequent analysis. 102621 Following manipulation of the isolated genetic material to provide Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention, the polynucleotides encoding the Sp35 antibodies are typically inserted in an expression vector for introduction into host cells that may be used to produce the desired quantity of Sp3 5 antibody. [02631 Recombinant expression of an antibody, or fragment, derivative or analog thereof, e.g., a heavy or light chain of an antibody which binds to a target molecule described herein, e.g., Sp35, requires construction of an expression vector containing a polynucleotide that encodes the antibody. Once a polynucleotide encoding an antibody molecule or a heavy or light chain of an antibody, or portion thereof (preferably containing the heavy or light chain variable domain), of the invention has been obtained, the vector for the production of the antibody molecule may be produced by recombinant DNA technology using techniques well known in the art. Thus, methods for preparing a protein by expressing a polynucleotide containing an antibody encoding nucleotide sequence are described herein. Methods which are well known to those skilled in the art can be used to construct expression vectors containing antibody coding sequences and appropriate transcriptional and translational control signals. These methods include, for example, in vitro recombinant DNA techniques, synthetic techniques, and in vivo genetic recombination. The invention, thus, provides replicable vectors comprising a nucleotide sequence encoding an antibody molecule of the invention, or a heavy or light chain thereof, or a heavy or light chain variable domain, operably linked to a promoter. Such vectors may include the nucleotide sequence encoding the constant region of the antibody molecule (see, e.g., PCT Publication WO 86/05807; PCT Publication WO 89/01036; and U.S. Pat. No. 5,122,464) and the variable domain of the antibody may be cloned into such a vector for expression of the entire heavy or light chain. [02641 The host cell may be co-transfected with two expression vectors of the invention, the first vector encoding a heavy chain derived polypeptide and the second vector encoding a light chain derived polypeptide. The two vectors may contain identical selectable markers which enable equal expression of heavy and light chain polypeptides. Alternatively, a single vector may be used which encodes both heavy and light chain polypeptides. In such situations, the light chain is advantageously placed before the heavy chain to avoid an excess of toxic free heavy chain (Proudfoot, Nature 322:52 (1986); Kohler, Proc. Nati. Acad. Sci. USA 77:2197 (1980)). The coding sequences for the heavy and light chains may comprise cDNA or genomic DNA. [02651 The term "vector" or "expression vector" is used herein to mean vectors used in accordance with the present invention as a vehicle for introducing into and expressing a desired gene in a host cell. As known to those skilled in the art, such vectors may easily be selected from the group consisting of plasmids, phages, viruses and retroviruses. In general, vectors compatible with the instant invention -82 will comprise a selection marker, appropriate restriction sites to facilitate cloning of the desired gene and the ability to enter and/or replicate in eukaryotic or prokaryotic cells. [02661 For the purposes of this invention, numerous expression vector systems may be employed. For example, one class of vector utilizes DNA elements which are derived from animal viruses such as bovine papilloma virus, polyoma virus, adenovirus, vaccinia virus, baculovirus, retroviruses (RSV, MMTV or MOMLV) or SV40 virus. Others involve the use of polycistronic systems with internal ribosome binding sites. Additionally, cells which have integrated the DNA into their chromosomes may be selected by introducing one or more markers which allow selection of transfected host cells. The marker may provide for prototrophy to an auxotrophic host, biocide resistance (e.g., antibiotics) or resistance to heavy metals such as copper. The selectable marker gene can either be directly linked to the DNA sequences to be expressed, or introduced into the same cell by cotransformation. Additional elements may also be needed for optimal synthesis of mRNA. These elements may include signal sequences, splice signals, as well as transcriptional promoters, enhancers, and termination signals. [0267] In particularly preferred embodiments the cloned variable region genes are inserted into an expression vector along with the heavy and light chain constant region genes (preferably human) synthetic as discussed above. In one embodiment, this is effected using a proprietary expression vector of Biogen IDEC, Inc., referred to as NEOSPLA (U.S. patent 6,159,730). This vector contains the cytomegalovirus promoter/enhancer, the mouse beta globin major promoter, the SV40 origin of replication, the bovine growth hormone polyadenylation sequence, neomycin phosphotransferase exon 1 and exon 2, the dihydrofolate reductase gene and leader sequence. This vector has been found to result in very high level expression of antibodies upon incorporation of variable and constant region genes, transfection in CHO cells, followed by selection in G418 containing medium and methotrexate amplification. Of course, any expression vector which is capable of eliciting expression in eukaryotic cells may be used in the present invention. Examples of suitable vectors include, but are not limited to plasmids pcDNA3, pHCMV/Zeo, pCR3.1, pEF1/His, pIND/GS, pRc/HCMV2, pSV40/Zeo2, pTRACER-HCMV, pUB6/V5-His, pVAX1, and pZeoSV2 (available from Invitrogen, San Diego, CA), and plasmid pCI (available from Promega, Madison, WI). In general, screening large numbers of transformed cells for those which express suitably high levels if immunoglobulin heavy and light chains is routine experimentation which can be carried out, for example, by robotic systems. Vector systems are also taught in U.S. Pat. Nos. 5,736,137 and 5,658,570, each of which is incorporated by reference in its entirety herein. This system provides for high expression levels, e.g., > 30 pg/cell/day. Other exemplary vector systems are disclosed e.g., in U.S. Patent 6,413,777. [02681 In other preferred embodiments the Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention may be expressed using polycistronic constructs such as those disclosed in United States Patent Application Publication No. 2003-0157641 Al, filed November - 83 18, 2002 and incorporated herein in its entirety. In these novel expression systems, multiple gene products of interest such as heavy and light chains of antibodies may be produced from a single polycistronic construct. These systems advantageously use an internal ribosome entry site (IRES) to provide relatively high levels of Sp35 antibodies, e.g., binding polypeptides, e.g., Sp35-specific antibodies or immunospecific fragments thereof in eukaryotic host cells. Compatible IRES sequences are disclosed in U.S. Pat. No. 6,193,980 which is also incorporated herein. Those skilled in the art will appreciate that such expression systems may be used to effectively produce the full range of Sp35 antibodies disclosed in the instant application. [02691 More generally, once the vector or DNA sequence encoding a monomeric subunit of the Sp35 antibody has been prepared, the expression vector may be introduced into an appropriate host cell. Introduction of the plasmid into the host cell can be accomplished by various techniques well known to those of skill in the art. These include, but are not limited to, transfection (including electrophoresis and electroporation), protoplast fusion, calcium phosphate precipitation, cell fusion with enveloped DNA, microinjection, and infection with intact virus. See, Ridgway, A. A. G. "Mammalian Expression Vectors" Vectors, Rodriguez and Denhardt, Eds., Butterworths, Boston, Mass., Chapter 24.2, pp. 470 472 (1988). Typically, plasmid introduction into the host is via electroporation. The host cells harboring the expression construct are grown under conditions appropriate to the production of the light chains and heavy chains, and assayed for heavy and/or light chain protein synthesis. Exemplary assay techniques include enzyme-linked immunosorbent assay (ELISA), radioinimunoassay (RIA), or fluorescence-activated cell sorter analysis (FACS), immunohistochemistry and the like. [0270] The expression vector is transferred to a host cell by conventional techniques and the transfected cells are then cultured by conventional techniques to produce an antibodyfor use in the methods described herein. Thus, the invention includes host cells containing a polynucleotide encoding an antibody of the invention, or a heavy or light chain thereof, operably linked to a heterologous promoter. In preferred embodiments for the expression of double-chained antibodies, vectors encoding both the heavy and light chains may be co-expressed in the host cell for expression of the entire immunoglobulin molecule, as detailed below. [02711 As used herein, "host cells" refers to cells which harbor vectors constructed using recombinant DNA techniques and encoding at least one heterologous gene. In descriptions of processes for isolation of antibodies from recombinant hosts, the terns "cell" and "cell culture" are used interchangeably to denote the source of antibody unless it is clearly specified otherwise. In other words, recovery of polypeptide from the "cells" may mean either from spun down whole cells, or from the cell culture containing both the medium and the suspended cells. [02721 A variety of host-expression vector systems may be utilized to express antibody molecules for use in the methods described herein. Such host-expression systems represent vehicles by which the - 84 coding sequences of interest may be produced and subsequently purified, but also represent cells which may, when transformed or transfected with the appropriate nucleotide coding sequences, express an antibody molecule of the invention in situ. These include but are not limited to microorganisms such as bacteria (e.g., E. coli, B. subtilis) transformed with recombinant bacteriophage DNA, plasmid DNA or cosmid DNA expression vectors containing antibody coding sequences; yeast (e.g., Saccharomyces, Pichia) transformed with recombinant yeast expression vectors containing antibody coding sequences; insect cell systems infected with recombinant virus expression vectors (e.g., baculovirus) containing antibody coding sequences; plant cell systems infected with recombinant virus expression vectors (e.g., cauliflower mosaic virus, CaMV; tobacco mosaic virus, TMV) or transformed with recombinant plasmid expression vectors (e.g., Ti plasmid) containing antibody coding sequences; or mammalian cell systems (e.g., COS, CHO, BLK, 293, 3T3 cells) harboring recombinant expression constructs containing promoters derived from the genome of mammalian cells (e.g., metallothionein promoter) or from mammalian viruses (e.g., the adenovirus late promoter; the vaccinia virus 7.5K promoter). Preferably, bacterial cells such as Escherichia coli, and more preferably, eukaryotic cells, especially for the expression of whole recombinant antibody molecule, are used for the expression of a recombinant antibody molecule. For example, mammalian cells such as Chinese hamster ovary cells (CHO), in conjunction with a vector such as the major intermediate early gene promoter element from human cytomegalovirus is an effective expression system for antibodies (Foecking et al., Gene 45:101 (1986); Cockett et al., Bio/Technology 8:2 (1990)). [02731 The host cell line used for protein expression is often of mammalian origin; those skilled in the art are credited with ability to preferentially determine particular host cell lines which are best suited for the desired gene product to be expressed therein. Exemplary host cell lines include, but are not limited to, CHO (Chinese Hamster Ovary), DG44 and DUXBI1 (Chinese Hamster Ovary lines, DHFR minus), HELA (human cervical carcinoma), CVI (monkey kidney line), COS (a derivative of CVI with SV40 T antigen), VERY, BHK (baby hamster kidney), MDCK, 293, W138, R1610 (Chinese hamster fibroblast) BALBC/3T3 (mouse fibroblast), HAK (hamster kidney line), SP2/O (mouse myeloma), P3x63-Ag3.653 (mouse myeloma), BFA-lclBPT (bovine endothelial cells), RAJI (human lymphocyte) and 293 (human kidney). CHO cells are particularly preferred. Host cell lines are typically available from commercial services, the American Tissue Culture Collection or from published literature. [0274] In addition, a host cell strain may be chosen which modulates the expression of the inserted sequences, or modifies and processes the gene product in the specific fashion desired. Such modifications (e.g., glycosylation) and processing (e.g., cleavage) of protein products may be important for the function of the protein. Different host cells have characteristic and specific mechanisms for the post-translational processing and modification of proteins and gene products. Appropriate cell lines or - 85 host systems can be chosen to ensure the correct modification and processing of the foreign protein expressed. To this end, eukaryotic host cells which possess the cellular machinery for proper processing of the primary transcript, glycosylation, and phosphorylation of the gene product may be used. [02751 For long-term, high-yield production of recombinant proteins, stable expression is preferred. For example, cell lines which stably express the antibody molecule may be engineered. Rather than using expression vectors which contain viral origins of replication, host cells can be transformed with DNA controlled by appropriate expression control elements (e.g., promoter, enhancer, sequences, transcription terminators, polyadenylation sites, etc.), and a selectable marker. Following the introduction of the foreign DNA, engineered cells may be allowed to grow for 1-2 days in an enriched media, and then are switched to a selective media. The selectable marker in the recombinant plasmid confers resistance to the selection and allows cells to stably integrate the plasmid into their chromosomes and grow to form foci which in turn can be cloned and expanded into cell lines. This method may advantageously be used to engineer cell lines which stably express the antibody molecule. [02761 A number of selection systems may be used, including but not limited to the herpes simplex virus thymidine kinase (Wigler et al., Cell 11:223 (1977)), hypoxanthine-guanine phosphoribosyltransferase (Szybalska & Szybalski, Proc. Natl. Acad. Sci. USA 48:202 (1992)), and adenine phosphoribosyltransferase (Lowy et al., Cell 22:817 1980) genes can be employed in tk-, hgprt or aprt-cells, respectively. Also, antimetabolite resistance can be used as the basis of selection for the following genes: dhfr, which confers resistance to methotrexate (Wigler et al., Natl. Acad. Sci. USA 77:357 (1980); O'Hare et al., Proc. Natl. Acad. Sci. USA 78:1527 (1981)); gpt, which confers resistance to mycophenolic acid (Mulligan & Berg, Proc. Natl. Acad. Sci. USA 78:2072 (1981)); neo, which confers resistance to the aminoglycoside G-418 Clinical Pharmacy 12:488-505; Wu and Wu, Biotherapy 3:87-95 (1991); Tolstoshev, Ann. Rev. Pharmacol. Toxicol. 32:573-596 (1993); Mulligan, Science 260:926-932 (1993); and Morgan and Anderson, Ann. Rev. Biochem. 62:191-217 (1993);, TIB TECH 11(5):155-215 (May, 1993); and hygro, which confers resistance to hygromycin (Santerre et al., Gene 30:147 (1984). Methods commonly known in the art of recombinant DNA technology which can be used are described in Ausubel et al. (eds.), Current Protocols in Molecular Biology, John Wiley & Sons, NY (1993); Kriegler, Gene Transfer and Expression, A Laboratory Manual, Stockton Press, NY (1990); and in Chapters 12 and 13, Dracopoli et al. (eds), Current Prolocols in Human Genetics, John Wiley & Sons, NY (1994); Colberre-Garapin et al., J. Mol. Biol. 150:1 (1981), which are incorporated by reference herein in their entireties. [02771 The expression levels of an antibody molecule can be increased by vector amplification (for a review, see Bebbington and Hentschel, The use of vectors based on gene amplification for the expression of cloned genes in mammalian cells in DNA cloning, Academic Press, New York, Vol. 3. (1987)). When a marker in the vector system expressing antibody is amplifiable, increase in the level of - 86 inhibitor present in culture of host cell will increase the number of copies of the marker gene. Since the amplified region is associated with the antibody gene, production of the antibody will also increase (Crouse et al., Mol. Cell. Biol. 3:257 (1983)). [0278] In vitro production allows scale-up to give large amounts of the desired polypeptides. Techniques for mammalian cell cultivation under tissue culture conditions are known in the art and include homogeneous suspension culture, e.g. in an airlift reactor or in a continuous stirrer reactor, or immobilized or entrapped cell culture, e.g. in hollow fibers, microcapsules, on agarose microbeads or ceramic cartridges. If necessary and/or desired, the solutions of polypeptides can be purified by the customary chromatography methods, for example gel filtration, ion-exchange chromatography, chromatography over DEAE-cellulose or (immuno-)affinity chromatography, e.g., after preferential biosynthesis of a synthetic hinge region polypeptide or prior to or subsequent to the HIC chromatography step described herein. [0279] Genes encoding Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can also be expressed non-mammalian cells such as bacteria or yeast or plant cells. Bacteria which readily take up nucleic acids include members of the enterobacteriaceae, such as strains of Escherichia coli or Salmonella; Bacillaceae, such as Bacillus subtilis; Pneumococcus; Streptococcus, and Haemophilus influenzae. It will further be appreciated that, when expressed in bacteria, the heterologous polypeptides typically become part of inclusion bodies. The heterologouspolypeptides must be isolated, purified and then assembled into functional molecules. Where tetravalent forms of antibodies are desired, the subunits will then self-assemble into tetravalent antibodies (WO02/096948A2). [02801 In bacterial systems, a number of expression vectors may be advantageously selected depending upon the use intended for the antibody molecule being expressed. For example, when a large quantity of such a protein is to be produced, for the generation of pharmaceutical compositions of an antibody molecule, vectors which direct the expression of high levels of fusion protein products that are readily purified may be desirable. Such vectors include, but are not limited, to the E. coli expression vector pUR278 (Ruther et al., EMBO J. 2:1791 (1983)), in which the antibody coding sequence may be ligated individually into the vector in frame with the lacZ coding region so that a fusion protein is produced; pIN vectors (Inouye & Inouye, Nucleic Acids Res. 13:3101-3109 (1985); Van Heeke & Schuster, J. Biol. Chem. 24:5503-5509 (1989)); and the like. pGEX vectors may also be used to express foreign polypeptides as fusion proteins with glutathione S-transferase (GST). In general, such fusion proteins are soluble and can easily be purified from lysed cells by adsorption and binding to a matrix glutathione-agarose beads followed by elution in the presence of free glutathione. The pGEX vectors are designed to include thrombin or factor Xa protease cleavage sites so that the cloned target gene product can be released from the GST moiety.

- 87 [02811 In addition to prokaryotes, eukaryotic microbes may also be used. Saccharomyces cerevisiae, or common baker's yeast, is the most commonly used among eukaryotic microorganisms although a number of other strains are commonly available, e.g., Pichiapastoris. [02821 For expression in Saccharomyces, the plasmid YRp7, for example, (Stinchcomb et al., Nature 282:39 (1979); Kingsman et al., Gene 7:141 (1979); Tschemper et al., Gene 10:157 (1980)) is commonly used. This plasmid already contains the TRP 1 gene which provides a selection marker for a mutant strain of yeast lacking the ability to grow in tryptophan, for example ATCC No. 44076 or PEP4 1 (Jones, Genetics 85:12 (1977)). The presence of the trpl lesion as a characteristic of the yeast host cell genome then provides an effective environment for detecting transformation by growth in the absence of tryptophan. [0283] In an insect system, Autographa californica nuclear polyhedrosis virus (AcNPV) is typically used as a vector to express foreign genes. The virus grows in Spodopterafrugiperda cells. The antibody coding sequence may be cloned individually into non-essential regions (for example the polyhedrin gene) of the virus and placed under control of an AcNPV promoter (for example the polyhedrin promoter). [02841 Once an antibody molecule of the invention has been recombinantly expressed, it may be purified by any method known in the art for purification of an immunoglobulin molecule, for example, by chromatography (e.g., ion exchange, affinity, particularly by affinity for the specific antigen after Protein A, and sizing column chromatography), centrifugation, differential solubility, or by any other standard technique for the purification of proteins. Alternatively, a preferred method for increasing the affinity of antibodies of the invention is disclosed in US 2002 0123057 Al. VIII. TREATMENT METHODS USING THERAPEUTIC Sp35 ANTIBODIES 102851 As described herein, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can relieve NgR1-mediated inhibition of axonal extension that normally takes place in CNS neurons. This is beneficial in situations where axonal extension or neurite sprouting is needed in the brain or spinal cord. Spinal cord injury, including partial or complete crush or severance, exemplifies a situation in which axonal extension is needed, but is normally inhibited through operation of the Nogo pathway. Examples of diseases or disorders in which axonal extension and/or neurite sprouting in the brain would be beneficial include stroke, multiple sclerosis, and other neurodegenerative diseases or disorders such as multiple sclerosis (MS), progressive multifocal leukoencephalopathy (PML), encephalomyelitis (EPL), central pontine myelolysis (CPM), adrenoleukodystrophy, Alexander's disease, Pelizaeus Merzbacher disease (PMZ), Globoid cell Leucodystrophy (Krabbe's disease) and Wallerian Degeneration, optic neuritis, transverse myelitis, amylotrophic lateral sclerosis (ALS), Huntington's disease, Alzheimer's disease, Parkinson's disease, - 88 spinal cord injury, traumatic brain injury, post radiation injury, neurologic complications of chemotherapy, stroke, neuropathy, acute ischemic optic neuropathy, vitamin E deficiency, isolated vitamin E deficiency syndrome, AR, Bassen-Kornzweig syndrome, Marchiafava-Bignami syndrome, metachromatic leukodystrophy, trigeminal neuralgia, Bell's palsy, spinal cord injury and all neurological diseases related to neuronal cell death. [0286] The inventors have further discovered that Sp 3 5 is expressed in oligodendrocytes, and contributes to oligodendrocyte biology. Soluble derivatives of Sp35, certain polynucleotides (e.g. RNAi), as well as certain antibodies which specifically bind to Sp35, as described herein act as antagonists to Sp35 function in oligodendrocytes, promoting proliferation, differentiation and survival of oligodendrocytes and promoting myelination of neurons in vitro and in vivo. This is beneficial in for diseases, disorders or conditions involving demyelination and dysmyelination. Examples of diseases or disorders in- which oligodendrocyte proliferation, differentiation and survival, and/or myelination or remyelination would be beneficial include multiple sclerosis (MS), progressive multifocal leukoencephalopathy (PML), encephalomyelitis (EPL), central pontine myelolysis (CPM), adrenoleukodystrophy, Alexander's disease, Pelizaeus Merzbacher disease (PMZ), Globoid cell Leucodystrophy (Krabbe's disease), Wallerian Degeneration, optic neuritis, transverse myelitis, amylotrophic lateral sclerosis (ALS), Huntington's disease, Alzheimer's disease, Parkinson's disease, spinal cord injury, traumatic brain injury, post radiation injury, neurologic complications of chemotherapy, stroke, acute ischemic optic neuropathy, vitamin E deficiency, isolated vitamin E deficiency syndrome, AR, Bassen-Kornzweig syndrome, Marchiafava-Bignami syndrome, metachromatic leukodystrophy, trigeminal neuralgia, and Bell's palsy. [0287] Accordingly, one embodiment of the present invention provides methods for treating spinal cord injury, diseases or disorders associated with inhibition of neuronal growth in the CNS, diseases or disorders associated with inhibition of oligodendrocyte growth or differentiation, and diseases involving demyelination or dysmyelination of CNS neurons in an animal suffering from such injury or disease or predisposed to contract such disease, the method comprising, consisting essentially of, or consisting of administering to the animal an effective amount of an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof. Antibodies of the invention are described herein, and include the monoclonal antibodies listed in Table 3A and 3B, antibodies which specifically bind to the same epitope as the monoclonal antibodies listed in Table 3A and 3B, antibodies which competitively inhibit binding of the monoclonal antibodies listed in Table 3A and 3B to Sp35, and antibodies comprising polypeptides derived from the monoclonal antibodies listed in Table 3A and 3B. [0288] A therapeutic Sp35 antibody to be used in treatment methods disclosed herein can be prepared and used as a therapeutic agent which promotes CNS neurite outgrowth, neuronal survival, axon guidance and axon regeneration, which promotes oligodendrocyte survival, growth, and/or - 89 differentiation, and which promotes myelination or remyelination of CNS neurons. Characteristics of suitable therapeutic Sp35 antibodies include: binding to Sp35 epitopes which result in blocking of Sp35 activity, binding to Sp35 with sufficient affinity to elicit a therapeutic effect, and binding to Sp35 preferentially to normal binding partners, e.g., Nogo Receptor. [0289] Therapeutic Sp35 antibodies may be monoclonal, chimeric or humanized antibodies, or fragments of antibodies that bind specifically to Sp35. The antibodies may be monovalent, bivalent, polyvalent, or bifunctional antibodies. Antibody fragments include without limitation Fab F(ab') 2 , and Fv fragments. [02901 Therapeutic Sp35 antibodies, or antigen-binding fragments, variants or derivatives thereof according to the invention can be used in unlabeled or unconjugated form, or can be coupled or linked to drugs, labels or stabilization agents which may or may not exert additional therapeutic effects. [02911 A specific dosage and treatment regimen for any particular patient will depend upon a variety of factors, including the particular Sp35 antibody, or antigen-binding fragment, variant or derivative thereof used, the patient's age, body weight, general health, sex, and diet, and the time of administration, rate of excretion, drug combination, and the severity of the particular disease being treated. Judgment of such factors by medical caregivers is within the ordinary skill in the art. The amount will also depend on the individual patient to be treated, the route of administration, the type of formulation, the characteristics of the compound used, the severity of the disease, and the desired effect. The amount used can be determined by pharmacological and pharmacokinetic principles well known in the art. [0292] In the methods of the invention the Sp35 antibodies, or antigen-binding fragments, variants or derivatives thereof may be administered directly to the nervous system, intracerebroventricularly, or intrathecally, e.g. into a chronic lesion of MS, as discussed in more detail below. [0293] In various embodiments, an Sp35 antibody as described above is an antagonist of Sp35 activity. In certain embodiments, for example, binding of an antagonist Sp35 antibody to Sp35, as expressed on neurons, blocks myelin-associated neurite outgrowth inhibition or neuronal cell death. In other embodiments, binding of the Sp35 antibody to Sp35, as expressed on oligodendrocytes, blocks inhibition of oligodendrocyte growth or differentiation, or blocks demyelination or dysmyelination of CNS neurons. [02941 In methods of the present invention, an Sp35 antibody, or an antigen-binding fragment, variant, or derivative thereof, in particular the Sp35 antibodies described herein, can be administered directly as a preformed polypeptide, or indirectly through a nucleic acid vector, to permit beneficial axonal outgrowth, promote oligodendrocyte proliferation, differentiation, and survival, and/or promote myelination or remyelination.

-90 [02951 In certain embodiments, a subject may be treated with a nucleic acid molecule encoding an Sp35 antibody, or antigen-binding fragment, variant, or analog thereof, e.g., in a vector. Doses for nucleic acids encoding polypeptides range from about 10 ng to I g, 100 ng to 100 mg, 1 pg to 10 mg, or 30-300 pg DNA per patient. Doses for infectious viral vectors vary from 10-100, or more, virions per dose. [0296] In some embodiments of the present invention an Sp35 antibody, or an antigen-binding fragment, variant, or derivative thereof is administered in a treatment method that includes: (1) transforming or transfecting an implantable host cell with a nucleic acid, e.g., a vector, that expresses an Sp35 antibody, or an antigen-binding fragment, variant, or derivative thereof; and (2) implanting the transformed host cell into a mammal, at the site of a disease, disorder or injury. For example, the transformed host cell can be implanted at the site of a spinal cord injury or at a site of dysmyelination. In some embodiments of the invention, the implantable host cell is removed from a mammal, temporarily cultured, transformed or transfected with an isolated nucleic acid encoding a an Sp35 antibody, and implanted back into the same mammal from which it was removed. The cell can be, but is not required to be, removed from the same site at which it is implanted. Such embodiments, sometimes known as ex vivo gene therapy, can provide a continuous supply of the Sp35 polypeptide, localized at the site of site of action, for a limited period of time. [02971 The methods for treating spinal cord injury, diseases or disorders associated with inhibition of neuronal growth in the CNS, diseases or disorders associated with inhibition of oligodendrocyte growth or differentiation, and diseases involving demyelination or dysmyelination of CNS neurons comprising administration of an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof of the invention are typically tested in vitro, and then in vivo in an acceptable animal model, for the desired therapeutic or prophylactic activity, prior to use in humans. Suitable animal models, including transgenic animals, are will known to those of ordinary skill in the art. For example, in vitro assays to demonstrate the therapeutic utility of Sp35 antibody described herein include the effect of an Sp35 antibody on a cell line or a patient tissue sample. The effect of the Sp35 antibody on the cell line and/or tissue sample can be determined utilizing techniques known to those of skill in the art, such as the assays disclosed elsewhere herein. In accordance with the invention, in vitro assays which can be used to determine whether administration of a specific Sp35 antibody is indicated, include in vitro cell culture assays in which a patient tissue sample is grown in culture, and exposed to or otherwise administered a compound, and the effect of such compound upon the tissue sample is observed. [0298] Supplementary active compounds also can be incorporated into the compositions of the invention. For example, a Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof of the invention may be coformulated with and/or coadministered with one or more additional therapeutic agents.

-91 [0299] The invention encompasses any suitable delivery method for a Sp35 antibody, or antigen binding fragment, variant, or derivative thereof of the invention to a selected target tissue, including bolus injection of an aqueous solution or implantation of a controlled-release system. Use of a controlled-release implant reduces the need for repeat injections. IX. PHARMACEUTICAL COMPOSITIONS AND ADMINISTRATION METHODS [0300] Methods of preparing and administering Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention to a subject in need thereof are well known to or are readily determined by those skilled in the art. The route of administration of the Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof may be, for example, oral, parenteral, by inhalation or topical. The term parenteral as used herein includes, e.g., intravenous, intraarterial, intraperitoneal, intramuscular, subcutaneous, rectal or vaginal administration. While all these forms of administration are clearly contemplated as being within the scope of the invention, a form for administration would be a solution for injection, in particular for intravenous or intraarterial injection or drip. Usually, a suitable pharmaceutical composition for injection may comprise a buffer (e.g. acetate, phosphate or citrate buffer), a surfactant (e.g. polysorbate), optionally a stabilizer agent (e.g. human albumin), etc. However, in other methods compatible with the teachings herein, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be delivered directly to the site of the adverse cellular population thereby increasing the exposure of the diseased tissue to the therapeutic agent. [03011 As previously discussed, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention may be administered in a pharmaceutically effective amount for the in vivo treatment of mammalian spinal cord injury, diseases or disorders associated with inhibition of neuronal growth in the CNS, diseases or disorders associated with inhibition of oligodendrocyte growth or differentiation, and diseases involving demyelination or dysmyelination of CNS. In this regard, it will be appreciated that the disclosed antibodies will be formulated so as to facilitate administration and promote stability of the active agent. Preferably, pharmaceutical compositions in accordance with the present invention comprise a pharmaceutically acceptable, non-toxic, sterile carrier such as physiological saline, non-toxic buffers, preservatives and the like. For the purposes of the instant application, a pharmaceutically effective amount of an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof, conjugated or unconjugated, shall be held to mean an amount sufficient to achieve effective binding to a target and to achieve a benefit, e.g., to ameliorate symptoms of a disease or disorder or to detect a substance or a cell. [03021 The pharmaceutical compositions used in this invention comprise pharmaceutically acceptable carriers, including, e.g., ion exchangers, alumina, aluminum stearate, lecithin, serum -92 proteins, such as human serum albumin, buffer substances such as phosphates, glycine, sorbic acid, potassium sorbate, partial glyceride mixtures of saturated vegetable fatty acids, water, salts or electrolytes, such as protamine sulfate, disodium hydrogen phosphate, potassium hydrogen phosphate, sodium chloride, zinc salts, colloidal silica, magnesium trisilicate, polyvinyl pyrrolidone, cellulose based substances, polyethylene glycol, sodium carboxymethylcellulose, polyacrylates, waxes, polyethylene-polyoxypropylene-block polymers, polyethylene glycol and wool fat. [0303] Preparations for parenteral administration includes sterile aqueous or non-aqueous solutions, suspensions, and emulsions. Examples of non-aqueous solvents are propylene glycol, polyethylene glycol, vegetable oils such as olive oil, and injectable organic esters such as ethyl oleate. Aqueous carriers include water, alcoholic/aqueous solutions, emulsions or suspensions, including saline and buffered media. In the subject invention, pharmaceutically acceptable carriers include, but are not limited to, 0.01-0.1M and preferably 0.05M phosphate buffer or 0.8% saline. Other common parenteral vehicles include sodium phosphate solutions, Ringer's dextrose, dextrose and sodium chloride, lactated Ringer's, or fixed oils. Intravenous vehicles include fluid and nutrient replenishers, electrolyte replenishers, such as those based on Ringer's dextrose, and the like. Preservatives and other additives may also be present such as for example, antimicrobials, antioxidants, chelating agents, and inert gases and the like. [03041 More particularly, pharmaceutical compositions suitable for injectable use include sterile aqueous solutions (where water soluble) or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions. In such cases, the composition must be sterile and should be fluid to the extent that easy syringability exists. It should be stable under the conditions of manufacture and storage and will preferably be preserved against the contaminating action of microorganisms, such as bacteria and fungi. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (e.g., glycerol, propylene glycol, and liquid polyethylene glycol, and the like), and suitable mixtures thereof. The proper fluidity can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. Suitable formulations for use in the therapeutic methods disclosed herein are described in Remington's Pharmaceutical Sciences, Mack Publishing Co., 16th ed. (1980). [0305} Prevention of the action of microorganisms can be achieved by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, ascorbic acid, thimerosal and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars, polyalcohols, such as mannitol, sorbitol, or sodium chloride in the composition. Prolonged absorption of the injectable compositions can be brought about by including in the composition an agent which delays absorption, for example, aluminum monostearate and gelatin.

-93 [0306] In any case, sterile injectable solutions can be prepared by incorporating an active compound (e.g., an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof, by itself or in combination with other active agents) in the required amount in an appropriate solvent with one or a combination of ingredients enumerated herein, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the active compound into a sterile vehicle, which contains a basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred methods of preparation are vacuum drying and freeze-drying, which yields a powder of an active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof. The preparations for injections are processed, filled into containers such as ampoules, bags, bottles, syringes or vials, and sealed under aseptic conditions according to methods known in the art. Further, the preparations may be packaged and sold in the form of a kit such as those described in co-pending U.S.S.N. 09/259,337 (US-2002-0102208 Al), which is incorporated herein by reference in its entirety. Such articles of manufacture will preferably have labels or package inserts indicating that the associated compositions are useful for treating a subject suffering from, or predisposed to autoimmune or neoplastic disorders. [03071 Parenteral formulations may be a single bolus dose, an infusion or a loading bolus dose followed with a maintenance dose. These compositions may be administered at specific fixed or variable intervals, e.g., once a day, or on an "as needed" basis. [0308] Certain pharmaceutical compositions used in this invention may be orally administered in an acceptable dosage form including, e.g., capsules, tablets, aqueous suspensions or solutions. Certain pharmaceutical compositions also may be administered by nasal aerosol or inhalation. Such compositions may be prepared as solutions in saline, employing benzyl alcohol or other suitable preservatives, absorption promoters to enhance bioavailability, and/or other conventional solubilizing or dispersing agents. 10309] The amount of an Sp35 antibody, or fragment, variant, or derivative thereof that may be combined with the carrier materials to produce a single dosage form will vary depending upon the host treated and the particular mode of administration. The composition may be administered as a single dose, multiple doses or over an established period of time in an infusion. Dosage regimens also may be adjusted to provide the optimum desired response (e.g., a therapeutic or prophylactic response). [0310] In keeping with the scope of the present disclosure, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention may be administered to a human or other animal in accordance with the aforementioned methods of treatment in an amount sufficient to produce a therapeutic effect. The Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be administered to such human or other animal in a conventional dosage form prepared by combining the antibody of the invention with a conventional pharmaceutically acceptable - 94 carrier or diluent according to known techniques. It will be recognized by one of skill in the art that the form and character of the pharmaceutically acceptable carrier or diluent is dictated by the amount of active ingredient with which it is to be combined, the route of administration and other well-known variables. Those skilled in the art will further appreciate that a cocktail comprising one or more species of Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention may prove to be particularly effective. [03111 Effective doses of the compositions of the present invention, for treatment of spinal cord injury, diseases or disorders associated with inhibition of neuronal growth in the CNS, diseases or disorders associated with inhibition of oligodendrocyte growth or differentiation, and diseases involving demyelination or dysmyelination of CNS vary depending upon many different factors, including means of administration, target site, physiological state of the patient, whether the patient is human or an animal, other medications administered, and whether treatment is prophylactic or therapeutic. Usually, the patient is a human but non-human mammals including transgenic mammals can also be treated. Treatment dosages may be titrated using routine methods known to those of skill in the art to optimize safety and efficacy. [03121 For treatment of spinal cord injury, diseases or disorders associated with inhibition of neuronal growth in the CNS, diseases or disorders associated with inhibition of oligodendrocyte growth or differentiation, and diseases involving demyelination or dysmyelination of CNS with an Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof, the dosage can range, e.g., from about 0.0001 to 100 mg/kg, and more usually 0.01 to 5 mg/kg (e.g., 0.02 mg/kg, 0.25 mg/kg, 0.5 mg/kg, 0.75 mg/kg, 1mg/kg, 2 mg/kg, etc.), of the host body weight. For example dosages can be 1 mg/kg body weight or 10 mg/kg body weight or within the range of 1-10 mg/kg, preferably at least 1 mg/kg. Doses intermediate in the above ranges are also intended to be within the scope of the invention. Subjects can be administered such doses daily, on alternative days, weekly or according to any other schedule determined by empirical analysis. An exemplary treatment entails administration in multiple dosages over a prolonged period, for example, of at least six months. Additional exemplary treatment regimes entail administration once per every two weeks or once a month or once every 3 to 6 months. Exemplary dosage schedules include 1-10 mg/kg or 15 mg/kg on consecutive days, 30 mg/kg on alternate days or 60 mg/kg weekly. In some methods, two or more monoclonal antibodies with different binding specificities are administered simultaneously, in which case the dosage of each antibody administered falls within the ranges indicated. [03131 Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be administered on multiple occasions. Intervals between single dosages can be daily, weekly, monthly or yearly. Intervals can also be irregular as indicated by measuring blood levels of target polypeptide or target molecule in the patient. In some methods, dosage is adjusted to achieve a - 95 plasma polypeptide concentration of 1-1000 pg/ml and in some methods 25-300 pg/ml. Alternatively, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be administered as a sustained release formulation, in which case less frequent administration is required. Dosage and frequency vary depending on the half-life of the antibody in the patient. The half-life of an Sp35 antibody can also be prolonged via fusion to a stable polypeptide or moeity, e.g., albumin or PEG. In general, humanized antibodies show the longest half-life, followed by chimeric antibodies and nonhuman antibodies. In one embodiment, the Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be administered in unconjugated form, In another embodiment, the Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be administered multiple times in conjugated form. In still another embodiment, Sp 3 5 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can be administered in unconjugated form, then in conjugated form, or vice versa. [03141 The compositions of the present invention may be administered by any suitable method, e.g., parenterally, intraventricularly, orally, by inhalation spray, topically, rectally, nasally, buccally, vaginally or via an implanted reservoir. The term "parenteral" as used herein includes subcutaneous, intravenous, intramuscular, intra-articular, intra-synovial, intrasternal, intrathecal, intrahepatic, intralesional and intracranial injection or infusion techniques. As described previously, Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention act in the nervous system to promote survival, proliferation and differentiation of oligodendrocytes and myelination of neurons and neuronal survival, axon regeneration and axon guidance. Accordingly, in the methods of the invention, the Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof are administered in such a way that they cross the blood-brain barrier. This crossing can result from the physico-chemical properties inherent in the Sp35 antibody molecule itself, from other components in a pharmaceutical formulation, or from the use of a mechanical device such as a needle, cannula or surgical instruments to breach the blood-brain barrier. Where the Sp35 antibody is a molecule that does not inherently cross the blood-brain barrier, e.g., a fusion to a moiety that facilitates the crossing, suitable routes of administration are, e.g., intrathecal or intracranial, e.g., directly into a chronic lesion of MS. Where the Sp35 antibody is a molecule that inherently crosses the blood-brain barrier, the route of administration may be by one or more of the various routes described below. In some methods, antibodies are administered as a sustained release composition or device, such as a Medipad'" device. Delivery across the blood brain barrier can be enhanced by a carrying molecule, such as anti-Fc receptor, transferrin, anti-insulin receptor or a toxin conjugate or penetration enhancer. [0315] The Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof used in the methods of the invention may be directly infused into the brain. Various implants for direct brain infusion of compounds are known and are effective in the delivery of therapeutic compounds to human -96 patients suffering from neurological disorders. These include chronic infusion into the brain using a pump, stereotactically implanted, temporary interstitial catheters, permanent intracranial catheter implants, and surgically implanted biodegradable implants. See, e.g., Gill et al., "Direct brain infusion of glial cell line-derived neurotrophic factor in Parkinson disease," Nature Med. 9: 589-95 (2003); Scharfen et al., "High Activity Iodine-125 Interstitial Implant For Gliomas," Int. J. Radiation Oncology Biol. Phys. 24(4):583-91 (1992); Gaspar et al., "Permanent 1251 Implants for Recurrent Malignant Gliomas," Int. J. Radiation Oncology Biol. Phys. 43(5):977-82 (1999); chapter 66, pages 577-580, Bellezza et al., "Stereotactic Interstitial Brachytherapy," in Gildenberg et al., Textbook of Stereotactic and Functional Neurosurgery, McGraw-Hill (1998); and Brem et al., "The Safety of Interstitial Chemotherapy with BCNU-Loaded Polymer Followed by Radiation Therapy in the Treatment of Newly Diagnosed Malignant Gliomas: Phase I Trial," J. Neuro-Oncology 26:111-23 (1995). [0316] The compositions may also comprise an Sp35 antibody dispersed in a biocompatible carrier material that functions as a suitable delivery or support system for the compounds. Suitable examples of sustained release carriers include semipermeable polymer matrices in the form of shaped articles such as suppositories or capsules. Implantable or microcapsular sustained release matrices include polylactides (U.S. Patent No. 3,773,319; EP 58,481), copolymers of L-glutamic acid and gamma-ethyl L-glutamate (Sidman et al., Biopolymers 22:547-56 (1985)); poly(2-hydroxyethyl-methacrylate), ethylene vinyl acetate (Langer et al., J. Biomed. Mater. Res. 15:167-277 (1981); Langer, Chem. Tech. 12:98-105 (1982)) or poly-D-(-)-3hydroxybutyric acid (EP 133,988). [03171 In some embodiments of the invention, an Sp 35 antibody, or antigen-binding fragment, variant, or derivative thereof of the invention is administered to a patient by direct infusion into an appropriate region of the brain. See, e.g., Gill et al., supra. Alternative techniques are available and may be applied to administer an Sp35 antibody according to the invention. For example, stereotactic placement of a catheter or implant can be accomplished using the Riechert-Mundinger unit and the ZD (Zamorano-Dujovny) multipurpose localizing unit. A contrast-enhanced computerized tomography (CT) scan, injecting 120 ml of omnipaque, 350 mg iodine/ml, with 2 mm slice thickness can allow three-dimensional multiplanar treatment planning (STP, Fischer, Freiburg, Germany). This equipment permits planning on the basis of magnetic resonance imaging studies, merging the CT and MRI target information for clear target confirmation. [0318] The Leksell stereotactic system (Downs Surgical, Inc., Decatur, GA) modified for use with a GE CT scanner (General Electric Company, Milwaukee, WI) as well as the Brown-Roberts-Wells (BRW) stereotactic system (Radionics, Burlington, MA) can be used for this purpose. Thus, on the morning of the implant, the annular base ring of the BRW stereotactic frame can be attached to the patient's skull. Serial CT sections can be obtained at 3 mm intervals though the (target tissue) region with a graphite rod localizer frame clamped to the base plate. A computerized treatment planning -97 program can be run on a VAX 11/780 computer (Digital Equipment Corporation, Maynard, Mass.) using CT coordinates of the graphite rod images to map between CT space and BRW space. [03191 Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention can optionally be administered in combination with other agents that are effective in treating the disorder or condition in need of treatment (e.g., prophylactic or therapeutic). X. DIAGNOSTICS [0320] The invention further provides a diagnostic method useful during diagnosis of neronal disorders or injuries, which involves measuring the expression level of Sp35 protein or transcript in tissue or other cells or body fluid from an individual and comparing the measured expression level with a standard Sp35 expression levels in normal tissue or body fluid, whereby an increase in the expression level compared to the standard is indicative of a disorder. [0321] Sp35-specific antibodies can be used to assay protein levels in a biological sample using classical immunohistological methods known to those of skill in the art (e.g., see Jalkanen, et al., J. Cell. Biol. 101:976-985 (1985); Jalkanen, et al., J. Cell Biol. 105:3087-3096 (1987)). Other antibody based methods useful for detecting protein expression include immunoassays, such as the enzyme linked immunosorbent assay (ELISA), immunoprecipitation, or western blotting. Suitable assays are described in more detail elsewhere herein. [03221 By "assaying the expression level of Sp35 polypeptide" is intended qualitatively or quantitatively measuring or estimating the level of Sp35 polypeptide in a first biological sample either directly (e.g., by determining or estimating absolute protein level) or relatively (e.g., by comparing to the cancer associated polypeptide level in a second biological sample). Preferably, Sp35 polypeptide expression level in the first biological sample is measured or estimated and compared to a standard Sp35 polypeptide level, the standard being taken from a second biological sample obtained from an individual not having the disorder or being determined by averaging levels from a population of individuals not having the disorder. As will be appreciated in the art, once the "standard" Sp35 polypeptide level is known, it can be used repeatedly as a standard for comparison. [03231 By "biological sample" is intended any biological sample obtained from an individual, cell line, tissue culture, or other source of cells potentially expressing Sp35. Methods for obtaining tissue biopsies and body fluids from mammals are well known in the art. [0324] Sp35 antibodies for use in the diagnostic methods described above include any Sp35 antibody which specifically binds to an Sp35 gene product, as described elsewhere herein.

-98 XI. IMMUNOASSAYS [03251 Sp 3 5 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention may be assayed for immunospecific binding by any method known in the art. The immunoassays which can be used include but are not limited to, competitive and non-competitive assay systems using techniques such as western blots, radioimmunoassays, ELISA (enzyme linked immunosorbent assay), "sandwich" immunoassays, immunoprecipitation assays, precipitin reactions, gel diffusion precipitin reactions, immunodiffusion assays, agglutination assays, complement-fixation assays, immunoradiometric assays, fluorescent immunoassays, protein A immunoassays, to name but a few. Such assays are routine and well known in the art (see, e.g., Ausubel et al., eds, Current Protocols in Molecular Biology, John Wiley & Sons, Inc., New York, Vol. 1 (1994), which is incorporated by reference herein in its entirety). Exemplary immunoassays are described briefly below (but are not intended by way of limitation). [03261 Immunoprecipitation protocols generally comprise lysing a population of cells in a lysis buffer such as RIPA buffer (1% NP-40 or Triton X-100, 1% sodium deoxycholate, 0.1% SDS, 0.15 M NaCl, 0.01 M sodium phosphate at pH 7.2, 1% Trasylol) supplemented with protein phosphatase and/or protease inhibitors (e.g., EDTA, PMSF, aprotinin, sodium vanadate), adding the antibody of interest to the cell lysate, incubating for a period of time (e.g., 1-4 hours) at 4.degree. C., adding protein A and/or protein G sepharose beads to the cell lysate, incubating for about an hour or more at 4.degree. C., washing the beads in lysis buffer and resuspending the beads in SDS/sample buffer. The ability of the antibody of interest to immunoprecipitate a particular antigen can be assessed by, e.g., western blot analysis. One of skill in the art would be knowledgeable as to the parameters that can be modified to increase the binding of the antibody to an antigen and decrease the background (e.g., pre-clearing the cell lysate with sepharose beads). For further discussion regarding immunoprecipitation protocols see, e.g., Ausubel et al., eds, Current Protocols in Molecular Biology, John Wiley & Sons, Inc., New York, Vol. 1 (1994) at 10.16.1. 103271 Western blot analysis generally comprises preparing protein samples, electrophoresis of the protein samples in a polyacrylamide gel (e.g., 8%-20% SDS-PAGE depending on the molecular weight of the antigen), transferring the protein sample from the polyacrylamide gel to a membrane such as nitrocellulose, PVDF or nylon, blocking the membrane in blocking solution (e.g., PBS with 3% BSA or non-fat milk), washing the membrane in washing buffer (e.g., PBS-Tween 20), blocking the membrane with primary antibody (the antibody of interest) diluted in blocking buffer, washing the membrane in washing buffer, blocking the membrane with a secondary antibody (which recognizes the primary antibody, e.g., an anti-human antibody) conjugated to an enzymatic substrate (e.g., horseradish peroxidase or alkaline phosphatase) or radioactive molecule (e.g., 32p or 1251) diluted in blocking buffer, washing the membrane in wash buffer, and detecting the presence of the antigen. One of skill in -99 the art would be knowledgeable as to the parameters that can be modified to increase the signal detected and to reduce the background noise. For further discussion regarding western blot protocols see, e.g., Ausubel et al., eds, Current Protocols in Molecular Biology, John Wiley & Sons, Inc., New York Vol. 1 (1994) at 10.8.1. [0328] ELISAs comprise preparing antigen, coating the well of a 96 well microtiter plate with the antigen, adding the antibody of interest conjugated to a detectable compound such as an enzymatic substrate (e.g., horseradish peroxidase or alkaline phosphatase) to the well and incubating for a period of time, and detecting the presence of the antigen. In ELISAs the antibody of interest does not have to be conjugated to a detectable compound; instead, a second antibody (which recognizes the antibody of interest) conjugated to a detectable compound may be added to the well. Further, instead of coating the well with the antigen, the antibody may be coated to the well. In this case, a second antibody conjugated to a detectable compound may be added following the addition of the antigen of interest to the coated well. One of skill in the art would be knowledgeable as to the parameters that can be modified to increase the signal detected as well as other variations of ELISAs known in the art. For further discussion regarding ELISAs see, e.g., Ausubel et al., eds, Current Protocols in Molecular Biology, John Wiley & Sons, Inc., New York, Vol. 1 (1994) at 11.2.1. [03291 The binding affinity of an antibody to an antigen and the off-rate of an antibody-antigen interaction can be determined by competitive binding assays. One example of a competitive binding assay is a radioimmunoassay comprising the incubation of labeled antigen (e.g., 3H or 1251) with the antibody of interest in the presence of increasing amounts of unlabeled antigen, and the detection of the antibody bound to the labeled antigen. The affinity of the antibody of interest for a particular antigen and the binding off-rates can be determined from the data by scatchard plot analysis. Competition with a second antibody can also be determined using radioimmunoassays. In this case, the antigen is incubated with antibody of interest is conjugated to a labeled compound (e.g., 3 H or 125J) in the presence of increasing amounts of an unlabeled second antibody. [0330] Sp35 antibodies, or antigen-binding fragments, variants, or derivatives thereof of the invention, additionally, be employed histologically, as in immunofluorescence, immunoelectron microscopy or non-immunological assays, for in situ detection of cancer antigen gene products or conserved variants or peptide fragments thereof. In situ detection may be accomplished by removing a histological specimen from a patient, and applying thereto a labeled Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof, preferably applied by overlaying the labeled antibody (or fragment) nto a biological sample. Through the use of such a procedure, it is possible to determine not only the p sence of Sp35 protein, or conserved variants or peptide fragments, but also its distribution in the examined tissue. Using the present invention, those of ordinary skill will readily perceive that any -100 of a wide variety of histological methods (such as staining procedures) can be modified in order to achieve such in situ detection. [03311 Immunoassays and non-immunoassays for Sp35 gene products or conserved variants or peptide fragments thereof will typically comprise incubating a sample, such as a biological fluid, a tissue extract, freshly harvested cells, or lysates of cells which have been incubated in cell culture, in the presence of a detectably labeled antibody capable of binding to Sp35 or conserved variants or peptide fragments thereof, and detecting the bound antibody by any of a number of techniques well known in the art. [0332] The biological sample may be brought in contact with and immobilized onto a solid phase support or carrier such as nitrocellulose, or other solid support which is capable of immobilizing cells, cell particles or soluble proteins. The support may then be washed with suitable buffers followed by treatment with the detectably labeled Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof. The solid phase support may then be washed with the buffer a second time to remove unbound antibody. Optionally the antibody is subsequently labeled. The amount of bound label on solid support may then be detected by conventional means. [03331 By "solid phase support or carrier" is intended any support capable of binding an antigen or an antibody. Well-known supports or carriers include glass, polystyrene, polypropylene, polyethylene, dextran, nylon, amylases, natural and modified celluloses, polyacrylamides, gabbros, and magnetite. The nature of the carrier can be either soluble to some extent or insoluble for the purposes of the present invention. The support material may have virtually any possible structural configuration so long as the coupled molecule is capable of binding to an antigen or antibody. Thus, the support configuration may be spherical, as in a bead, or cylindrical, as in the inside surface of a test tube, or the external surface of a rod. Alternatively, the surface may be flat such as a sheet, test strip, etc. Preferred supports include polystyrene beads. Those skilled in the art will know many other suitable carriers for binding antibody or antigen, or will be able to ascertain the same by use of routine experimentation. [0334] The binding activity of a given lot of Sp35 antibody, or antigen-binding fragment, variant, or derivative thereof may be determined according to well known methods. Those skilled in the art will be able to determine operative and optimal assay conditions for each determination by employing routine experimentation. [03351 There are a variety of methods available for measuring the affinity of an antibody-antigen interaction, but relatively few for determining rate constants. Most of the methods rely on either labeling antibody or antigen, which inevitably complicates routine measurements and introduces uncertainties in the measured quantities.

-101 [0336] Surface plasmon reasonance (SPR) as performed on BlAcore offers a number of advantages over conventional methods of measuring the affinity of antibody-antigen interactions: (i) no requirement to label either antibody or antigen; (ii) antibodies do not need to be purified in advance, cell culture supernatant can be used directly; (iii) real-time measurements, allowing rapid semi quantitative comparison of different monoclonal antibody interactions, are enabled and are sufficient for many evaluation purposes; (iv) biospecific surface can be regenerated so that a series of different monoclonal antibodies can easily be compared under identical conditions; (v) analytical procedures are fully automated, and extensive series of measurements can be performed without user intervention. BIAapplications Handbook, version AB (reprinted 1998), BIACORE code No. BR-1001-86; BlAtechnology Handbook, version AB (reprinted 1998), BIACORE code No. BR-1001-84. [0337] SPR based binding studies require that one member of a binding pair be immobilized on a sensor surface. The binding partner immobilized is referred to as the ligand. The binding partner in solution is referred to as the analyte. In some cases, the ligand is attached indirectly to the surface through binding to another immobilized molecule, which is referred as the capturing molecule. SPR response reflects a change in mass concentration at the detector surface as analytes bind or dissociate. [0338] Based on SPR, real-time BIAcore measurements monitor interactions directly as they happen. The technique is well suited to determination of kinetic parameters. Comparative affinity ranking is extremely simple to perform, and both kinetic and affinity constants can be derived from the sensorgram data. [0339] When analyte is injected in a discrete pulse across a ligand surface, the resulting sensorgram can be divided into three essential phases: (i) Association of analyte with ligand during sample injection; (ii) Equilibrium or steady state during sample injection, where the rate of analyte binding is balanced by dissociation from the complex; (iii) Dissociation of analyte from the surface during buffer flow. [03401 The association and dissociation phases provide information on the kinetics of analyte ligand interaction (ka and kd, the rates of complex formation and dissociation, k/ka = KD). The equilibrium phase provides information on the affinity of the analyte-ligand interaction (KD). 103411 BlAevaluation software provides comprehensive facilities for curve fitting using both numerical integration and global fitting algorithms. With suitable analysis of the data, separate rate and affinity constants for interaction can be obtained from simple BlAcore investigations. The range of affinities measurable by this technique is very broad ranging from mM to pM. [0342] Epitope specificity is an important characteristic of a monoclonal antibody. Epitope mapping with BlAcore, in contrast to conventional techniques using radioimmunoassay, ELISA or other surface adsorption methods, does not require labeling or purified antibodies, and allows multi-site -102 specificity tests using a sequence of several monoclonal antibodies. Additionally, large numbers of analyses can be processed automatically. [03431 Pair-wise binding experiments test the ability of two MAbs to bind simultaneously to the same antigen. MAbs directed against separate epitopes will bind independently, whereas MAbs directed against identical or closely related epitopes will interfere with each other's binding. These binding experiments with BlAcore are straightforward to carry out. [03441 For example, one can use a capture molecule to bind the first Mab, followed by addition of antigen and second MAb sequentially. The sensorgrams will reveal: 1. how much of the antigen binds to first Mab, 2. to what extent the second MAb binds to the surface-attached antigen, 3. if the second MAb does not bind, whether reversing the order of the pair-wise test alters the results. [0345] Peptide inhibition is another technique used for epitope mapping. This method can complement pair-wise antibody binding studies, and can relate functional epitopes to structural features when the primary sequence of the antigen is known. Peptides or antigen fragments are tested for inhibition of binding of different MAbs to immobilized antigen. Peptides which interfere with binding of a given MAb are assumed to be structurally related to the epitope defined by that MAb. [03461 The practice of the present invention will employ, unless otherwise indicated, conventional techniques of cell biology, cell culture, molecular biology, transgenic biology, microbiology, recombinant DNA, and immunology, which are within the skill of the art. Such techniques are explained fully in the literature. See, for example, Molecular Cloning A Laboratory Manual, 2nd Ed., Sambrook et al., ed., Cold Spring Harbor Laboratory Press: (1989); Molecular Cloning: A Laboratory Manual, Sambrook et al., ed., Cold Springs Harbor Laboratory, New York (1992), DNA Cloning, D. N. Glover ed., Volumes I and II (1985); Oligonucleotide Synthesis, M. J. Gait ed., (1984); Mullis et al. U.S. Pat. No: 4,683,195; Nucleic Acid Hybridization, B. D. Hames & S. J. Higgins eds. (1984); Transcription And Translation, B. D. Hames & S. J. Higgins eds. (1984); Culture Of Animal Cells, R. I. Freshney, Alan R. Liss, Inc., (1987); Immobilized Cells And Enzymes, IRL Press, (1986); B. Perbal, A Practical Guide To Molecular Cloning (1984); the treatise, Methods In Enzymology, Academic Press, Inc., N.Y.; Gene Transfer Vectors For Mammalian Cells, J. H. Miller and M. P. Calos eds., Cold Spring Harbor Laboratory (1987); Methods In Enzymology, Vols. 154 and 155 (Wu et al. eds.); Immunochemical Methods In Cell And Molecular Biology, Mayer and Walker, eds., Academic Press, London (1987); Handbook Of Experimental Immunology, Volumes I-IV, D. M. Weir and C. C. Blackwell, eds., (1986); Manipulating the Mouse Embryo, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., (1986); and in Ausubel et al., Current Protocols in Molecular Biology, John Wiley and Sons, Baltimore, Maryland (1989). [03471 General principles of antibody engineering are set forth in Antibody Engineering, 2nd edition, C.A.K. Borrebaeck, Ed., Oxford Univ. Press (1995). General principles of protein engineering - 103 are set forth in Protein Engineering, A Practical Approach, Rickwood, D., et al., Eds., IRL Press at Oxford Univ. Press, Oxford, Eng. (1995). General principles of antibodies and antibody-hapten binding are set forth in: Nisonoff, A., Molecular Immunology, 2nd ed., Sinauer Associates, Sunderland, MA (1984); and Steward, M.W., Antibodies, Their Structure and Function, Chapman and Hall, New York, NY (1984). Additionally, standard methods in immunology known in the art and not specifically described are generally followed as in Current Protocols in Immunology, John Wiley & Sons, New York; Stites et al. (eds) , Basic and Clinical -Immunology (8th ed.), Appleton & Lange, Norwalk, CT (1994) and Mishell and Shiigi (eds), Selected Methods in Cellular Immunology, W.H. Freeman and Co., New York (1980). [0348] Standard reference works setting forth general principles of immunology include Current Protocols in Immunology, John Wiley & Sons, New York; Klein, J., Immunology: The Science of Self Nonself Discrimination, John Wiley & Sons, New York (1982); Kennett, R., et al., eds., Monoclonal Antibodies, Hybridoma: A New Dimension in Biological Analyses, Plenum Press, New York (1980); Campbell, A., "Monoclonal Antibody Technology" in Burden, R., et al., eds., Laboratory Techniques in Biochemisty and Molecular Biology, Vol. 13, Elsevere, Amsterdam (1984), Kuby Immunnology 4 ed. Ed. Richard A. Goldsby, Thomas J. Kindt and Barbara A. Osborne, H. Freemand & Co. (2000); Roitt, I., Brostoff, J. and Male D., Immunology 6d* ed. London: Mosby (2001); Abbas A., Abul, A. and Lichtman, A., Cellular and Molecular Immunology Ed. 5, Elsevier Health Sciences Division (2005); Konterniann and Dubel, Antibody Engineering, Springer Verlan (2001); Sambrook and Russell, Molecular Cloning: A Laboratory Manual. Cold Spring Harbor Press (2001); Lewin, Genes VIII, Prentice Hall (2003); Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Press (1988); Dieffenbach and Dveksler, PCR Primer Cold Spring Harbor Press (2003). [03491 All of the references cited above, as well as all references cited herein, are incorporated herein by reference in their entireties. EXAMPLES EXAMPLE 1 Sp35 is involved in oligodendrocyte biology [0350] Oligodendrocytes mature through several developmental stages from A2B5 progenitor cells (which express A2B5), differentiating into pre-myelinating oligodendrocytes (which express 01 and 04) and finally into mature myelinating oligodendrocytes (which express 01, 04 and MBP). Thus, by monitoring the presence and absence of the A2B5, 01, 04 and MBP markers it is possible to determine a given cell's developmental stage and to evaluate the role of Sp35-Fc in oligodendrocyte biology. For -104 a general review of oligodendrocyte biology, see, e.g., Baumann and Pham-Dinh, Physiol. Rev. 81: 871-927 (2001). [0351] Monoclonal antibodies against 04, MBP and CNPase were from Sternberger Monoclonals; antibody to APC (clone CC-1; ref. 29) was from Calbiochem. Other antibodies were to pIII tubulin (Covance), Sp35 (Biogen Idec), Fyn (Santa Cruz Biotechnology) and phospho-Fyn (Biosource). Monoclonal antibodies against A2B5 are available from Chemicon. Sp35 is expressed in oligodendrocytes [0352] The expression of Sp35 in purified rat P13 CG neuron, P2 oligodendrocyte, and P4 astrocyte cultures was analyzed by polymerase chain reaction after reverse transcription (RT-PCR). A kit from Ambion, Inc. was used to extract mRNA from the rat brain cells according to the manufacturer's instructions. Semi-quantitative RT-PCR was carried out using forward primer 5' AGAGACATGCGATTGGTGA 3' (SEQ ID NO:344), and reverse primer 5' AGAGATGTAGACGAGGTCATT 3' (SEQ ID NO:345) showed high expression in neurons, lower expression in oligodendrocytes, and no expression in astrocytes. [03531 The expression of Sp35 in oligodendrocytes was confirmed by in situ hybridization in sections derived from adult rat optic nerve. Rat optic nerve sections were prepared and processed as described in Mi et al., "Sp35 is a component of the Nogo-66 receptor/p75 signaling complex," Nat Neurosci. 7: 221-28 (2004) and probed with digoxigenin-labeled Sp35 antisense or sense RNAs using the first 500 nucleotides of the Sp35 coding sequence. The sections were stained according to the manufacturers' instructions using a Tyramide Signal Amplification kit (Amersham Biosciences) and a fluorescent anti-digoxigenin conjugated antibody kit (Perkin Elmer). For combined in situ and immunofluorescence analyses, the sections were first probed with digoxigenin-labeled RNAs and then with antibodies, e.g. CC1 antibody (Calbiochem; a marker of mature oligodendrocytes) or anti-Sp35 antibody. We observed that oligodendrocytes that hybridized to an antisense Sp35 probe also co stained with an antibody to CC1 (data not shown). No specific labeling was observed using a sense Sp35 probe. Sp35 expression in oligodendrocytes also was confirmed by immunohistochemistry studies of tissue sections from the lateral ventricle region of P7 rat cortex. A majority of cortical cells that labeled with CC1 antibody also labeled with anti-Sp35 antibody. Data not shown. The specificity of the interaction was confirmed by preadsorption of the anti-Sp35 antibody with Sp35-Fc (see Example 2), which eliminated the signal. Sp35-specific RNAi knockdown of Sp35 expression promotes oligodendrocyte growth and differentiation [03541 Sp35-specific RNAi was used to ablate Sp35 expression in oligodendrocyte precursor cells to examine how Sp35 contributes to oligodendrocyte growth and differentiation. 50,000 A2B5 -105 oligodendrocyte precursor cells were infected with lentivirus carrying Sp35-specific RNAi sequence or control RNAi prepared as follows. [0355] Murine and rat Sp35 DNA sequences were compared to find homologous regions to use for candidate small-hairpin RNAs (shRNA). CH324, for lentivirus expression of Sp35 RNAi, was constructed by annealing oligonucleotides LV1-035 and LV1-036 and ligating to HpaI and AoI digested pLL3.7. The pLL3.7 vector, additional methodology and virus production were as described in Rubinson et al., Nat. Genet. 33, 401-06 (2003). The Sp35 RNAi oligonucleotides were purchased from MWG and have the following sequences: LV1-035 (sense oligo) 5' - TGA TCG TCA TCC TGC TAG ACT TCA AGA GAG TCT AGC AGG ATG ACG ATC TTT TIT C - 3' (SEQ ID NO:346) and LV1-036 (antisense oligo) 5'- TCG AGA AAA AAG ATC GTC ATC CTG CTA GAC TCT CTT GAA GTC TAG CAG GAT GAC GAT CA - 3' (SEQ ID NO:347). [03561 Control RNAi was designed with the same oligonucleotide sequences except for the nucleotide changes indicated in lower-case letters: 5'-TGA TCc TCA TcC ttC Tat ACT TCA AGA GAG TgT AGC AGG ATG AcG ATC TTT TTT CTC GA-3' (SEQ ID NO:348) and 5'-TCG AGA AAA AAG ATC GTC ATC CTG CTA GAC TCT CTT GAA GTa TAG aAG GAT GAC GAT CA-3'. (SEQ ID NO:349). [03571 Prior to producing the lentivirus, DNA from pLL3.7 or candidate shRNA in pLL3.7 were cotransfected with murine Sp35-HA tagged plasmid at a ratio of 5 to 1 into CHO cells in a 6-well format. Knockdown was analyzed by western blot detection of Sp 3 5-HA tag from transfected CHO cell lysates as well as by northern blot of total RNA prepared from duplicate wells. The blot was probed with a fragment of Sp35 cDNA. Assays were performed 48 hours post-transfection. As expected, there was a 10-fold reduction of Sp35 mRNA in CH324 RNAi-treated CHO cells relative to control-treated cells. Data not shown. RNAi lentiviruses carrying green fluorescent protein (GFP) were generated as described in Rubinson et al. In cultures treated with either control or Sp35 RNAi, approximately 80% of the oligodendrocytes were GFP positive. Total cell number was not altered by the RNAi treatments. To quantify the effects of RNAi on differentiation, only GFP-expressing oligodendrocytes were counted. 10358] Enriched populations of oligodendrocytes were grown from female Long Evans P2 rats as described by Conn, Meth. Neurosci. 2:1-4 (Academic Press; 1990) with modifications as follows. Briefly, the forebrain was dissected and placed in Hank's buffered salt solution (HBSS; Invitrogen). The tissue was cut into 1-mm fragments and was incubated at 37*C for 15 min in 0.01% trypsin and 10 pg/ml DNase. Dissociated cells were plated on poly-L-lysine-coated T75 tissue culture flasks and were grown at 37 0 C for 10 d in DMEM medium with 20% fetal calf serum (Invitrogen). Oligodendrocyte precursors (A2B5*) were collected by shaking the flask overnight at 200 rpm at 37"C, resulting in a 95% pure population. Cultures were maintained in high-glucose Dulbecco's modified Eagle's medium (DMEM) with FGF/PDGF (10 ng/ml; Peprotech) for 1 week. Removal of FGF/PDGF allowed A2B5+ - 106 cells to differentiate into 04* premyelinating oligodendrocytes after 3-7 d, and to differentiate into 04 and MBP* mature oligodendrocytes after 7-10 d. These differentiation states are readily apparent from changes in morphology: A2B5* cells are bipolar in shape, 04+ premyelinating oligodendrocytes have longer and more branched processes and MBP* mature oligodendrocytes contain myelin sheet structures between processes. [0359] A2B5 oligodendrocyte precursor cells were infected with the lentivirus containing the CH324 RNAi. The resulting cells were cultured for 3 days and the number of 04-positive (a marker for oligodendrocyte differentiation) oligodendrocytes was counted. Endogenous Sp35 expression was reduced by infection with Sp35 RNAi lentivirus and was confirmed by RT-PCR. Reduction of Sp35 resulted in more highly differentiated, mature oligodendrocytes as compared with control infected cells, as was evident by increases in the length of cell processes and by the presence of abundant myelin sheet structures (data not shown). In cells that expressed Sp35 RNAi, there were three times as many mature (04-positive) oligodendrocytes as in control cultures. These data indicate that Sp35 may negatively regulate oligodendrocyte differentiation. Dominant-negative Sp35 promotes oligodendrocyte growth and differentiation [0360] Lentiviral vectors that express wild-type and a dominant-negative form of Sp35 were constructed. DNA sequence encoding mouse full length Sp35 (FL-Sp35, amino acid residues 34-614 of SEQ ID NO:2) was amplified by PCR using primers 5' - GAG GAT CTC GAC GCG GCC GCA TGG AGA CAG ACA CAC TCC TG - 3' (SEQ ID NO:350) and 5' - GGG GCG GAA TTG GAT CCT CAC AGA TCC TCT TCT GAG ATG AG-3' (SEQ ID NO:351) and inserted into the HRST IRESeGFP lentiviral vector at the NotI and BamHI sites. Similarly, DNA sequence encoding dominant negative Sp35 (DN-Sp35, amino acid residues 34-581 of SEQ ID NO:2) was amplified by PCT using primers 5' - GAG GAT CTC GAC GCG GCC GCA TGG AGA CAG ACA CAC TCC TG - 3' (SEQ ID NO:352) and 5' - GAT ACG GAT CCT CAG CCT TTG CCC CGG CTC CAT AGA AAC AGC 3' (SEQ ID NO:353). The FL-Sp35 and DN-Sp35 plasmids were transfected into 293 cells to produce lentivirus as described by Rubinson et al., "A lentivirus-based system to functionally silence genes in primary mammalian cells, stem cells and transgenic mice by RNA interference," Nat. Genet. 33: 401 06 (2003). Oligodendrocytes were infected with lentivirus at 2 MOI per cell and confirmed expression of FL-Sp35 and DN-Sp35 by western blot. [03611 DN-Sp35 promoted oligodendrocyte differentiation, producing an increase in the number of mature oligodendrocytes. In contrast, overexpression of full-length Sp35 (FL-Sp35) had the opposite effect and inhibited differentiation, as was evident by a reduction in the number of mature oligodendrocytes as compared with the control (data not shown).

- 107 EXAMPLE 2 Construction and purification of Sp35-Fc fusion protein [03621 A construct was made fusing the extra-cellular portion of human Sp35 (residues 1-532) to the hinge and Fc region of human IgG1 to study the biological function of Sp35. A partial coding sequence for human Sp35 was obtained by PCR from clone 227.2 using the forward primer 5' - CAG CAG GTC GAC GCG GCC GCA TGC TGG CGG GGG GCG T - 3' (SEQ ID NO:354) and reverse primer 5' - CAG CAG GTC GAC CTC GCC CGG CTG GTT GGC CAA CCA GCC GGG CGA GGT CGA CCT CGA GG - 3' (SEQ ID NO:355). [03631 The blunt-end PCR product was subcloned into the SrfI site of the PCR SCRIPT AMP vector (Stratagene) to create PCR SCRIPT AMP-Sp35. A Sall fragment was isolated from PCR SCRIPT AMP-Sp35 and subcloned into the PCRCAMP Ig vector (derivative of Stratagene vector PCR SCRIPT AMP). In the PCRCAMP Ig vector, the hinge and Fc gamma sequence is subcloned as a Sall(5') to NotI(3') fragment. The Sail Sp35 fragment was subcloned into the SalI site of the PCRCAMP Ig vector thereby fusing the Sp35 signal sequence and extracellular domain (codons 1-532) in-frame with sequences encoding the hinge and Fc region of human Igl. Correct isolates were identified, and a NotI fragment encompassing the Sp35 Fc fragment was subcloned into the single NotI cloning site of the CHO expression vector, PV90 (Biogen Idec). The resulting plasmid was confirmed by DNA sequencing aand designated GT123. [0364] Stable cell lines expressing the Sp35-Fc fusion protein were generated by electroporation of CHO host cells DG44 with plasmid GT123. Transfected CHO cells were cultured in alpha minus MEM in the presence of 10% dialyzed serum and 4 mM glutamine to select for nucleoside-independent growth. Fourteen days post-transfection, cells were fed fresh media. To screen for cells expressing Sp35-Fc, CHO cells were labeled with phycoerythrin (PE)-labeled goat anti-human IgG (Jackson Labs) and subjected to high speed flow cytometry sorting in a FACS Mo-Flo (Cytomation). The cells that expressed the highest levels of Sp 3 5-Fc were selected. These cells were expanded in culture for 7 days, then re-labeled and re-sorted. Cells expressing the highest levels of Sp35-Fc were isolated as individual clones in 96-well plates. These clones were grown for two weeks and then fed fresh media one day prior to FACS analysis to check for expression levels. Clones that expressed the highest levels of Sp35-Fc were expanded, and frozen cell banks were established. The cell lines were adapted to grow in suspension culture in the serum-free media BCM16. The titer of Sp35-Fc produced by these clones was determined by growing cell lines at 37*C for 4-5 passages, then growing the cells to 50% maximal cell density and culturing them for 10-15 days at 28 0 C until the viable cell density dropped to 75%. At this time, the culture media were harvested, cleared of cells and debris by centrifugation, and the culture supernatants titered for Sp 3 5-Fc levels by Western blot analysis using an anti-human Ig antibody (Jackson Lab) as the probe.

-108 [0365] Sp35-Fc fusion protein was purified from the clarified culture medium as follows: 9 ml of IM IHEPES pH 7.5 was added to 900 ml of conditioned medium. The medium was batch loaded for 3 hr at 4 0 C onto 3 ml of Protein A Sepharose (Amersham Bioscience). The resin was collected in a 1.5 cm (I.D.) column, and washed four times with 3 ml PBS, two times with 4 ml of PBS containing 800 mM NaCl, and then again with 3 ml of PBS. The Sp35-Fc was eluted from the column with 25 mM NaH2PO4, pH 2.8 and 100 mM NaCI in 1.5 ml fractions and neutralized by adding 75 pl of 0.5 M NaH2PO4, pH 8.6. Peak protein-containing fractions were identified by absorbance at 280 nm, pooled, and subjected to further purification on a 1 mL Protein A column. Prior to loading, NaCI was added to 600 mM and HEPES, pH 7.5 to 50 mM. The column was washed twice with 600 ptl of 10 mM HEPES pH 7.5 and 1 M NaCl , and then with 1 ml PBS. Sp35-Fc was eluted from the column with 25 mM NaH2PO4, pH 2.8 and 100 mM NaCl, collecting 0.5 mL fractions, and neutralized by adding 25 pl of 0.5 M NaH2PO4, pH 8.6. Peak protein-containing fractions were identified by absorbance at 280 rim and pooled. By reducing SDS-PAGE, the Sp35-Fc protein migrated as a single band (>95% pure) with an apparent mass of 90 kDa. Under non-reducing conditions, the protein ran as a dimer with an approximate mass of 180 kDa. The purified Sp35-Fc protein was aliquoted and stored at -70*C. EXAMPLE 3 Production of Sp35-Specific Monoclonal Antibodies [03661 Anti-Sp35 Antibodies that specifically bind an Sp35 polypeptide of the invention were made using the following methods and procedures. A. Antibody Screening Assays 1. ELISA Assay [0367] Sp35-Fc (0.5 pg in 50 jil of 0.1 M sodium bicarbonate buffer, pH 9.0) was added to each well of 96-well MaxiSorpTM plates (NuncTM). The plates were then incubated at 37*C for 1 hour or 4*C for 16 hours. Non-specific binding sites on the plates were blocked using 25 mM HEPES, pH 7.4 containing 0.1% BSA, 0.1% ovalbumin, 0.1% (5% (w/v) nonfat dry milk in 150mM NACE) and 0.00 1% azide. Dilutions of serum or hybridoma supernatants (for example, serial three-fold dilutions) were added across each row of the plate, and incubated at 25*C for 1 hour. After washing three times with PBS, 50 pil of a 1:10,000 dilution of horseradish peroxidase-conjugated goat anti-mouse secondary antibody (Jackson ImmunoResearch Inc.) was added to each well and incubated further for 1 hour. After three washings, color was developed by TMB (Pierce) and stopped with 2 M sulfuric acid. Color intensity was monitored in a spectrophotometer at 450 nm.

- 109 2. FACS Assay [03681 COS-7 cells were labeled with 0.1 pM CellTrackerTM Green CMFDA (Molecular Probes, Eugene, OR) as described by the vendor. Equal volumes of CellTrackerTM labeled control cells were mixed with washed Sp35-COS-7 cells (produced by transient transfection of Sp35 expression vector) before incubation with anti-Sp35 test sera or hybridoma supernatants. Fifty microliters of the cell mixture was dispensed into each well of a 96-well V-bottom polystyrene plates (Costar® 3877, Coming, NY) and 100 ptl of mouse serum, hybridoma supernatant, or a control anti-Sp35 antibody was added. After incubation at 4*C for 30 minutes, the cells were washed and incubated with 50 pl of phycoerythrin-conjugated affinity pure F(ab') 2 fragment goat anti-mouse IgG Fc gamma specific second antibody (1:200, Jackson ImmunoResearch Laboratory, West Grove, PA) in PBS. At the end of the incubation, the cells were washed twice with PBS and suspended in 200 pl of PBS containing 1% fetal bovine serum (FBS), and subjected to FACS analyses. Alternately, Sp35-COS-7 cells were mixed with mouse serum or hybridoma supernatant and then treated with R-phycoerythrin-conjugated goat anti mouse secondary antibody and directly subjected to standard FACS analyses. B. Hybridoma Production of Murine Monoclonal Anti-Sp35 Antibodies [0369] Eight-week-old female RBF mice (Jackson Labs, Bar Harbor, ME) were immunized intraperitoneally with emulsion containing 50 Ig Sp35-Fc (amino acids 34 to 532 of SEQ ID NO:2 fused to the hinge and Fc region of human IgG1), produced as described in Example 2 or were immunized intraperitoneally with an emulsion containing 50 [tg of human Sp35-Fc, and 50 [d complete Freund's adjuvant (Sigma® Chemical Co., St. Louis, MO) once every two weeks. Sera from the immunized mice were collected before the first immunization and 1 week after the second and third immunizations, and anti-Sp35 antibody titers were measured by FACS assay on Sp35-expressing COS 7 cells as described above. A booster final dose was given after the third immunization and three days prior to when hybridoma fusions were initiated. [0370] Sera from mice immunized with the various Sp35 peptides were screened by ELISA as described above. Mice that were positive for antibodies that specifically bound Sp35 expressing COS-7 cells were identified by flow cytometry (FACS) as described above, and were sacrificed. Splenocytes were isolated from the mice and fused to the FL653 myeloma (an APRT-derivative of a Ig-/HGPRT Balb/c mouse myeloma, maintained in DMEM containing 10% FBS, 4500 mg/L glucose, 4 mM L glutamine, and 20 mg/mil 8-azaguanine) as described in Monoclonal Antibodies. Hybridomas: A New Dimension in Biological Analyses, ed. Kennett, R.H., McKearn, T.J. and Bechtol, K.B. New York: Plenum Press (1982). Fused cells were plated into 24- or 48-well plates (Corning Glass Works, Corning, NY), and fed with adenine, aminopterin and thymidine (AAT, available from Sigma® Chemical Co., St. Louis, MO) containing culture medium. AAT resistant cultures were screened by -110 ELISA or flow cytometry as described above for binding to either Sp35-COS-7 cells or to Sp35-Fc. Positive hybridomas were further subcloned by limiting dilution. [0371] Seventeen hybridoma cell lines producing monoclonal antibodies produced from mice immunized with Sp35-Fc were isolated. Properties of the hybridoma-derived monoclonal antibodies are shown in Tables 3A and 3B. [03721 Polynucleotides encoding the variable domains (VH and VL) of monoclonal antibodies 1A7, 2F3, 3P1D10.2C3 and 3PlEll.3B7 were isolated by PCR, cloned and were subjected to sequence analysis by the following method. Total RNA was extracted from hybridoma cells using Qiagen@ RNeasy@ mini kit.and cDNA was generated from the isolated RNA by RT PCR, using standard conditions. A cocktail of primers were used for the RT-PCR. A prefered set of primers included a primer with the 5' of the primer hybridizing to the signal sequence and the 3' end of the primer hybridizing to the constant domain 3' of the FR4/constant domain junction. This allows for the amplification of an intact variable domain with no ambiguities about the monoclonal antibody N terminus and the V/C junction. One of skill in the art will recognize that primer sets need to be modified for amplifying different templates and for different PCR conditions. Occasionally, the presence of highly abundant nonproductive messages (e.g. the CDR3-FR4 frameshifted nonproductive light chain from the fusion partner) or nonspecific productive messages can be produced and complicate the cloning of variable chains. One solution is to use N-terminal sequence data from the authentic purified antibody to design a degenerate primer to enable cloning. Alternatively, one can use "universal framework" primers, such as those described in Orlandi et al, PNAS 86:3833 (1989), which "fix" the N- and C-termini of the variable domains (i.e. the N-terminus of FRI and the C-terminus of FR4 are primer-determined). [0373] Additionally, sequence data, for designing more effective primers, can be obtained from the bulk RT-PCR products which have been gel purified and then sequenced. The PCR product can also be subcloned using, for example, the TOPO Cloning Kit (Invitrogen) then sequence. Sequence data is then obtained from multiple independent subclones or gel purified fragments to firnly establish the consensus sequence. [0374] The sequence of the light chain of the PlEl 1.3B7 was determined by using a cocktail of 5' murine kappa light chain signal sequence primers: (i) 5' GGG GAT ATC CAC CAT GGA TTT TCA GGT GCA GAT TT CAG 3' (SEQ ID NO:356), (ii) 5' GGG GAT ATC CAC CAT GRA GTC ACA KAC YCA GGT CTT YRT A 3' (SEQ ID NO:357), (iii) 5' GGG GAT ATC CAC CAT GAA GTT GCC TGT TAG GCT GTT G 3' (SEQ ID NO:358), and (iv) 5' GGG GAT ATC CAC CAT GAG GKC CCC WGC TCA GYT YCT KGG A 3' (SEQ ID NO:359), with a single 3' urine kappa constant domain primer: 5' GCG TCT AGA ACT GGA TGG TGG GAG ATG GA 3' (SEQ ID NO:4), where K=G/T, R=A/G, W=A/T and Y=C/T. The resulting PCR product was subcloned and multiple - 111 independent subclones were sequenced. The deduced consensus sequence was consistent with the Edman degradation sequencing data. Sequencing indicated that the degenerate signal sequence 5' primer 5' GGG GAT ATC CAC CAT GRA GTC ACA KAC YCA GGT CTT YRT A 3' (SEQ ID NO:357) was the one that had yielded the 3PIE11.3B7 light chain variable domain during the amplification. [0375] The 3P1E11.3B7 heavy chain sequence was determined using a cocktail of murine heavy chain signal sequence 5' PCR primers: (i) 5' GGG GAT ATC CAC CAT GGR ATG SAG CTG KGT MAT SCT CIT 3', (SEQ ID NO:360) (ii) 5' GGG GAT ATC CAC CAT GRA CTT CGG GYT GAG CTK GGT TTT 3' (SEQ ID NO:361), and (iii) 5' GGG GAT ATC CAC CAT GGC TGT CTT GGG GCT GCT CTT CT 3'(SEQ ID NO:362), with a degenerate murine IgG CH1 constant domain 3' primer 5' AGG TCT AGA AYC TCC ACA CAC AGG RRC CAG TGG ATA GAC 3' (SEQ ID NO:363), where K=G/T, M= A/C, R=A/G, and Y=C/T. PCR using this cocktail of primers, with a variety of different cycling conditions, failed to yield a heavy chain variable domain sequence in which the deduced N-terminus was consistent with that determined by Edman degradation sequence of the purified 3P1E11.3B7 antibody. We therefore used heavy chain universal primers: FRl 5' AGG TSM ARC TGC AGS AGT CWG G 3' (SEQ ID NO:364) and FR4 5' TGA GGA GAC GGT GAC CGT GGT CCC TTG GCC CCA G 3' (SEQ ID NO:365), where M= A/C, R=A/G, S=C/G, and W=A/T. This set yielded a murine heavy chain variable domain whose deduced sequence was consistent with the empirical 3P1E1 .3B7 data. [0376] In order to verify that the heavy chain variable domain N- and C-termini were authentic and not primer-determined, another PCR reaction was performed with a degenerate signal sequence primer 5' ATG GAR TGY AAY TGG ATH CTN CCN TTY A 3' (SEQ ID NO:366). and the aforementioned constant domain 3' primer 5' AGG TCT AGA AYC TCC ACA CAC AGG RRC CAG TGG ATA GAC 3' (SEQ ID NO:367), where H=A/C/T, N=A/C/G/T, R=A/G, and Y=C/T. The design of the degenerate signal sequence primer was based upon signal sequences of the best hits derived from a TFASTA search of the Genbank rodent sequence database queried with the 3P1E11.3B7 consensus deduced FR1 sequence from the PCR reaction with the "universal primer" described above. This PCR yielded a product with a complete murine heavy chain variable domain. [0377] The complete 3P lE .3B7 murine variable domains were used (with silent mutagenesis as necessary to introduce restriction sites) in conjunction with human IgG1 and kappa constant domain cDNAs to construct chimeric heavy and light chain cDNAs, respectively. The full-length immunoglobulin cDNAs were subcloned into an expression vector called pNE001, a derivative of the commercial EBV mammalian cell episomal expression vector pCEP4. The heavy and light chain expression vectors (called pXW372 and pXW363, respectively) were co-transfected into 293-EBNA cells. Western blot analysis (probed with human IgG-specific reagents) of conditioned medium from -112 transiently transfected cells confirmed the expression of chimeric 3P1E11.3B7-huIgGl, kappa mAb. The resulting 3PlE11.3B7 VH and VL polypeptide sequences are shown in Tables 6 and 8 and are SEQ ID NOs: 173 and 209, respectively. The heavy and light chain sequences for the 1A7, 2F3, and 3P1D10.2C3 monoclonal antibodies were determined by similar methods. C. Identification of Anti-Sp35 Monoclonal Antibodies by Phage Display 103781 Anti-Sp35 monoclonal antibody Fab fragments were identified and isolated from phage display libraries as described in Hoet et al., Nat. Biotech. 23:344-348 (2005); Rauchenberger, et al., J. Biol. Chem. 278:194-205 (2003); and Knappik, et al., J. Mol. Biol. 296:57-86 (2000), all of which are incorporated herein by reference in their entireties. [03791 The MorphoSys Fab-phage display library HuCAL@ GOLD ("Phage Display Library-2" in Table 3B), which comprises humanized synthetic antibody variable regions was screened against recombinant human soluble Sp35-Fc protein by standard ELISA AND IHC screening methods. See, e.g., Ostendorp, R., Frisch, C. and Urban M, "Generation, engineering and production of human antibodies using HuCAL@." Antibodies, Volume 2 Novel Technologies and Therapeutic Use. New York: Kluwer Academic/Plenum 13-52 (2004). Fab-phages that specifically bound to Sp35 were purified and characterized. Properties of these phage display-derived monoclonal antibody Fab fragments are shown in Table 3B as "phage display library-2-derived monoclonal Fab fragments." Isolated Fab-phage 1968 was selected for further analysis. EXAWLE 4 Immunoprecipitation of Sp35 by Anti- Sp35 Monoclonal Antibodies [03801 To perform the immunoprecipitation, COS-1 cells expressing Sp35, fused to a hemaglutinin (HA) tag on the N-terminus, were produced by transiently transfecting COS-1 cells with a DNA construct which expresses the full-length Sp35 protein with an HA tag. Cells were harvested 48 hr after transfection and were lysed in 1 ml lysis buffer (50mM HEPES, pH 7.5, 150mM NaCl, 1.5mM MgC1 2 , 1mM EGTA, 1% Triton X-100 and 10% glycerol) for 30 min at 4*C. After centrifugation at 14,000xg for 15 min, the supernatants were incubated with ProteinA/G-Sepharose beads (Santa Cruz) at 4aC for I hr, and then incubated at 4*C for 1 hr with either the 1A7 or the 2F3 anti-Sp35 marine monoclonal antibodies. The beads were washed 3 times with lysis buffer, boiled in Laemmli sample buffer, subjected to 4-20% SDS-PAGE, and analyzed by Western blotting using an antibody which recognizes the HA tag. As shown on the SDS-PAGE gel, monoclonal antibodies 1A7 and 2F3, immunoprecipitated human and marine Sp35 (Fig. 1). As shown in Fig. 1, monoclonal antibody 2F3 -113 strongly immunoprecipitated both human and murine Sp35, while monoclonal antibody 1A7, which strongly immunoprecipitated human Sp35, only recognized murine Sp35 protein weakly. Similarly, monoclonal antibodies 1G7, 2B10, 2F3, 3P4C2.2D2, 3P4C8.2G9, LiO1, Li03, Li05, Li06, Li07, Li08, Lill and Lil2 immunoprecipitate human or mouse or human and mouse Sp35 (See Table 3B). Additionally, Li08 immunoprecipitates AP-Sp35 and monoclonal antibodies 1B6.4 and 3E3.1 immunoprecipitate endogenous Sp35 (See Table 3B). EXAMPLE 5 Anti-Sp35 Antibody Binding Specifically to Sp35 determined by ELISA [0381] In order to determine which regions of the Sp35 polypeptide were bound by the various hybridoma- and phage display-derived monoclonal antibodies produced in Example 2, an ELISA assay was performed using a panel of truncated Sp35 polypeptides, each fused to the hinge and Fc regions of IgGl by the methods described in Example 1. The panel consisted of the following Sp35 fragments: amino acids 34-425 of SEQ ID NO:2, amino acids 417-532 of SEQ ID NO:2, amino acids 417-493 of SEQ ID NO:2, and amino acids 34-532 of SEQ ID NO:2. Ovalbumin and BSA were used as controls. As shown in Table 3B, hybridoma-derived mAbs 2F3, 2B10, 3A3, 3P4c2.2d2, and 3P4c8.2g9, and Fab-phage derived mAbs 3383, 3563, 3564, 3565, 3568, 3569, 3570, and 3582 all specifically bound to the 1-417 and 1-534 Sp35 fragments, suggesting that these antibodies bind to epitopes in the LRR region of Sp35. Hybridoma-derived Mabs 1A7, 3P1Bl1F9, 3PlDlO.2C3, 3P1E11.3B7, 3P2C63G10.2H7, 2P2C9.2G4, 3P4A61D9, and 394C51D8, and Fab-phage-derived Mabs 3495, 3566, 3567, and 1968 specifically bound to the 34-532 Sp35 fragment and weakly bound to the 417-532 Sp35, suggesting that these antibodies likely bind to epitopes which at least include a portion of Sp35 C-terminal to the LRR region. In similar experiments, these latter antibodies also specifically bound an Sp35 polypeptide consisting of amino acids 34-534 of human Sp35 and low affinity to mouse and rat Sp35. The affinity of these latter antibodies for mouse and rat Sp35 was restored to the level seen using human Sp35 when amino acid 419 of the mouse or rat Sp35 is changed from histidine (H) to arginine (R). Arginine is the amino acid at position 419 in human Sp35. The KD for monoclonal antibody 1A7 was determined to be lOnM (1 x 10 9 M) for binding human Sp35 and 20pM (2 x 10~5 M) for binding murine Sp35. For Ap-Sp35 ELISA to detect the antibodies bound to the 417 to 532 region, the ELISA was performed as follows: The Mabs were coated onto ELISA plates, then incubated either with an Sp35-AP fusion protein at 4*C overnight followed by AP-linked anti-human (H+L) (1:5,000, Jackson ImmunoResearch) at RT for 1 hr, or with AP-fusion proteins at 4*C overnight. AP substrate was then developed by 10 mg/ml 4NPP in 0.1 M Glycin, 1 mM MgC1 2 , 1 mM ZnCl 2 , pH 10.5, and read at O.D. 405.

- 114 EXAMPLE 6 Anti-Sp35 Antibody binding Specifically to Sp35 determined by FACS [03821 To further characterize the binding properties of hybridoma-derived anti-Sp35 mAbs 1A7 and 2F3 produced as described in Example 3, binding to both fixed and live COS-7 or 293 cells expressing mouse or human Sp35 was compared. Sp35 transfected and non-transfected cells were fixed and subject to FACS analysis (FACS: Cells transfected with human or mouse Sp35 or vector control were dissociated from culture plates, washed with 2% FBS/PBS, and incubated with primary antibody at 1 ptg/ml on ice for 1 hr. The cells were washed 3 times with 2% FBS/PBS, then incubated with PE labeled secondary antibody (1:100, JacksonhmmunoResearch) on ice for 30 min. After 2 washes with 2% FBS/PBS, cells were fixed in 2% PFA and subjected to FACS analysis by PE.) FACS result showed that MAbs 1A7 and 2F3 bound to COS-7 or 293 cells expressing Sp35, but not bind to control cells with no Sp35 expression (Fig 2). EXAMPLE 7 Neurite Outgrowth Assay [0383] To test the ability of the hybridoma-derived and Fab-phage-derived monoclonal antibodies produced above to reverse the inhibitory effect of CNS myelin inhibitors, e.g., OMgp, on neurons, Lab Tek@ culture slides (4 wells) were coated with 0.1mg/ml poly-D-lysine (Sigma@). Ap-OMgp (1pg/spot) or PBS was spotted as 3 p1l drops. Lab-Tek@ slides were then rinsed and coated with 10 Ig/ml laminin (GibcoTM). Dorsal root ganglions (DRG's) from P6-7 Sprague Dawley rat pups were dissociated with 1 mg/mI collagenase type 1 (Worthington), triturated with fire-polished Pasteur pipettes pre-plated to enrich in neuronal cells and finally plated at 10,000 cells/well on the pre-coated Lab-Tek@ culture slides. Ten gg/ml of mAb 1A7 or 2F3 were added immediately after plating of the DRGs. The culture medium was F12 (available from Gibco/Invitrogen) containing 5% heat inactivated donor horse serum, 5% heat inactivated fetal bovine serum and 50 ng/ml mouse nerve growth factor (mNGF) and incubated at 37*C and 5% CO 2 for 6 hours. Following incubation, the slides were fixed in 4% paraformaldehyde/20% sucrose and stained with anti-BIII-tubulin TUJ1 antibody (Covance) after 16 hours. [0384] As secondary antibody anti-mouse Alexa- Fluor@ 594 (Molecular Probes) diluted 1:300 was added to the slides and incubated for 2 hours at room temperature. The slides were coverslipped with Gel/MountTM (BiomedaTM). 5x digital images were acquired with OpenLabTM software (Improvision, Inc., Lexington, MA), and the images were analyzed for quantification of neurite outgrowth using the OPENLABTM software, all according to manufacturer's specified parameters.

-115 [0385] Both MAbs 1A7 and 2F3 protected DRG neurons from OMgp-mediated inhibition of neurite outgrowth. (Fig 3). EXAMPLE 8 Monoclonal antibody lA7 promotes functional recovery in the rat Spinal Cord Injury model [0386] Spinal cord injury ("SCI") was induced by dorsal over-hemi-section as follows, modified from methods described previously (Li, S. et al. J. Neurosci. 24, 10511-10520 (2004)). Anesthetized female Long Evans rats (7 weeks old, Charles River) were given pre-operative analgesia (Buprenorphine/Buprenex, 0.05mg/kg s.c.) and tranquillized (Midazolam, 2.5mg/kg i.p.) and a dorsal hemi-section was performed at thoracic vertebra 6/7 completely interrupting the main dorsomedial and the dorsolateral corticospinal tract (CST). The dorsal and dorso-lateral components of the corticospinal tract (CST) were completely interrupted and the ventral portion of the CST left intact. The ventral tissue bridge remaining after hemi-section constituted approximately 20% of the cord in both treatment groups (data not shown). [0387] Hindlimb function was quantified using the Basso-Beattie-Bresnahan (BBB) open field scoring method (Eby, M.T. et al., J. Biol. Chenz. 275, 15336-15342 (2000), incorporated herein by reference) and all animals sustained marked functional deficits after SCI, with almost complete hindlimb paralysis the day after surgery. Immediately after CST transection, an intrathecal catheter was inserted into the subarachnoid space at T7 and connected to a primed mini-osmotic pump (Alzet model 2004, Alza Corp) inserted into the subcutaneous space. Mini-osmotic pumps delivered Human IgG isotype control protein (5mg/ml) or monoclonal antibody 1A7 (4.8mg/ml) continuously at a rate of 0.25p/h over 5 weeks. Control (Human IgG-treated) animals recovered substantial function over the 5 week duration of the experiment, but plateaued at 3-4 weeks, ultimately attaining a mean BBB score of 9 & 0.45 (Fig. 7). In contrast, continuous intrathecal infusion of 1A7 for 5 weeks after spinal cord transection resulted in significantly improved BBB scores over the control animals by 5 weeks with a continued improvement in function in the 2-5 week timeframe, reaching a mean BBB score of 11.1 0.7 (Fig. 4). These results demonstrate that treatment with anti-Sp35 monoclonal antibody 1A7 promoted recovery of function after spinal cord injury as demonstrated by an increase in BBB score, axon regeneration and less axon retraction observed by immunohistochemical staining of the axons.

- 116 EXAMPLE 9 Anti-Sp35 antibodies 1A7, 2F3, 3P1DlO.2C3, 3PlEl1.3B7, 6P4F4.1D3, 6P4F4.1F9, 7P1D5.1G9, Li05, Li06, Li08, Lil3, Li28, Li33, DOS and D08 promote myelination in vitro [0388] The role of anti-Sp35 antibodies 1A7 and 2F3 in myelination was investigated in vitro by treating co-cultures of dorsal root ganglion (DRG) neurons and oligodendrocytes with anti-Sp35 antibodies 1A7 and 2F3 and testing for myelination by immunohistochemistry and Western blotting. For these studies, it was necessary to first generate primary cultures of DRG neurons and of oligodendrocytes. [0389] Female Long Evans rat E14-E17 embryonic dorsal root ganglia were cultured as described by Plant et al., J. Neurosci. 22:6083-91 (2002). Dissected DRGs were plated on poly-L-lysine-coated cover slips (100 ptg/ml) for 2 weeks. The cells were incubated in the presence of fluorodeoxyuridine for days 2-6 and in NLA medium containing I x B27, 100 ng/ml NGF (Gibco) for days 8-11. 103901 Female Long Evans post-natal day 2 (P2) rat oligodendrocytes were cultured as described by Conn, Meth. Neurosci. 2:1-4 (Academic Press; 1990) with modifications as follows. Briefly, the forebrain was extirpated from P2 rats and placed in cold HBSS medium (Gibco). The tissue fragments were cut into 1 mm pieces and incubated at 37*C for 15 min in 0.01% trypsin and 10 pg/ml DNase. Dissociated cells were plated on a poly-L-lysine coated T75 tissue culture flasks and grown in DMEM with 20% fetal bovine serum at 37 0 C for 10 days. A2B5-positive oligodendrocytes were collected by shaking the flasks overnight at 200 rpm at 37*C. The A2B5 oligodendrocytes were cultured for 7 days in DMEM (Gibco) containing 25 mM D-glucose, 4 mM L-glutamine, 1 mM sodium pyruvate, 50 [Lg/ml human apo-transferrin, 5 pig/mi bovine pancreatic insulin, 30 nM sodium selenate, 10 nM hydrocortisone, 10 nM D-biotin, 1 mg/ml BSA, lOng/ml FGF and PDGF (Peprotech). The cells were then harvested by trypsinization. The cells then co-cultured with the DRG neurons in the presence or absence of 1, 3, 10, or 30 ig/ml of anti Sp 3 5 monoclonal antibodies 1A7 or 2F3, or a negative control antibody in NLA medium containing 2% fetal bovine serum, 50 jig/ml ascorbic acid, 100 ng/ml NGF (Gibco). An effective antibody dose to administer in such an assay has been determined to be in the range of 0.1 pig/ml to 10 gg/ml, depending upon the antibody. One of skill in the art would be able to determine an effective dose using assays described herein. [03911 The culture medium was changed and the various monoclonal antibodies were replenished every three days. After 30 days at 37*C, the co-cultured cells were stained by immunohistochemical staining ("IHC") for neurofilaments with anti-BIII-tubulin antibody to identify axons, or anti-MBP antibody to identify oligodendrocytes (Fig. 4A-E). Co-cultured cells were also lysed and subjected to Western blot analysis to quantify the MBP (Fig. 4G). Based on IHC and Western blot analyses, co cultured cells treated with anti-Sp35 antibodies 1A7 and 2F3 showed increased survival of oligodendrocyte and neurons, increased numbers of bundled axons and increased numbers of MBP -117 positive cells (Fig. 4F, 10-fold more MBP-positive cells when compared to control-antibody treated co cultures. [0392] In a similar experiment, oligodendrocyte and DRG co-cultures were incubated in the presence or absence of anti-Sp35 antibodies Li05 and Li06, or a negative control antibody. Co-cultured cells were lysed and subjected to Western blot analysis to quantify the MBP (Fig. 8). Based on Western blot analyses, co-cultured cells treated with anti-Sp35 antibodies LiOS and Li06 showed increased numbers of MBP positive cells, similar to co-cultured cells treated with 3, 10 and 30 pg of Sp35-Fc (LINGO-1-Fc). [03931 In similar experiments oligodendrocyte and DRG co-cultures were incubated in the presence or absence of anti-Sp35 antibodies 3P1D1O.2C3, 3P1El1.3B7, 6P4F4.1D3, 6P4F4.1F9, 7P1D5.1G9, LiO8, Lil3, Li28, and Li33 and also promoted myelination. Similiarly, full-length antibodies DOS and D08 also promoted myelination. [03941 These results indicated that treatment of DRG-oligodendrocyte cocultures with anti-Sp35 antibodies 1A7, 2F3, 3PlD1O.2C3, 3P1E11.3B7, 6P4F4.1D3, 6P4F4.1F9, 7P1D5.1G9, LiO5, Li06, LiO8, Lil3, Li28, Li33, D05 and D08 promoted mature oligodendrocyte axon interactions and myelination compared to control-antibody treated co-cultures. EXAMPLE 10 Anti-Sp35 antibody 1A7 promotes oligodendrocyte survival and myelination in vivo [03951 Adult wild-type C57B1/6 male mice were fed cuprizone (0.2% milled with ground mouse chow by weight) for 6 weeks to induce demyelination within the corpus callosum according to the method described by Morell P et al., Mol Cell Neurosci. 12:220-7 (1998). Briefly, anti-Sp35 monoclonal antibody 1A7 was stereotactically injected into the demyelinating corpus callosum at weeks 2, 2.5, and 3 weeks of cuprizone feeding, by the method described below. Control mice were stereotactically injected at the same intervals with sterilized media containing control antibody. After the 6 weeks of cuprizone feeding was completed, the mice were returned to a normal diet for 2, 4 and 6 weeks (ground mouse chow only) to allow remyelination. [0396] The 1A7 and control monoclonal antibodies were delivered as follows. The cuprizone treated mice were anesthetized with ketamine (80 mg/kg body weight) and xylazine (10 mg/kg body weight) and positioned in an immobilization apparatus designed for stereotactic surgery (David Kopf Instruments). The scalp was opened and the sterile compounds injected (1 [tM in 1 ml of HBSS) unilaterally into the acutely demyelinated corpus callosum of the wild-type recipient mice with a 10 1d Hamilton syringe using stereotactic coordinates of 0.7 mm posterior and 0.3 mm lateral to bregma at a depth of 1.7 mm (Messier et al., Pharnacol. Biochem. Behav. 63: 313-18 (1999)). Additional control - 118 recipient mice were stereotactically injected with HBSS containing no compounds. The opening in the skull was filled with Gelfoam, and the area was swabbed with penicillin and streptomycin (Gibco) and the wound was sutured. Mice were sacrificed every week of the experiment after injection and their brains removed and processed for molecular, biochemical and histological analysis. [03971 The animals receiving anti-Sp35 antibody 1A7 treatment showed increased mature oligodendrocyte survival (based on CC1 antibody staining, Fig. 5A) and axon myelination by IHC using anti-MBP protein antibody or luxol fast blue (Fig. 5B). CCl antibody-positive oligodendrocytes were quantitated at four weeks and 6 weeks (Fig. SC). These results indicated that anti-Sp35 antibody 1A7 treatment promoted mature oligodendrocyte survival and axon myelination compared to control antibody treated mice. Similarly, animals receiving the 1A7 antibody in a lysolecithin model of demyelination also promoted axon myelination compared to control animals (data not shown). EXAMPLE 11 Anti-Sp35 antibody 1A7 promotes retinal ganglion cell (RGC) survival in the optic nerve transection model [03981 Anti-Sp35 antibody 1A7 was tested in an optic nerve transection model, which investigates factors that affect neuronal function. Young adult female Sprague Dawley (SD) rats were used in this study. The right optic nerve of each animal was transected intraorbitally 1.5 mm from the optic disc. A piece of gelfoam soaked with 6% Fluoro-Gold (FG) was applied to the newly transected site right behind the optic disc to label the surviving retinal ganglion cells (RGCs). The animals were divided into three groups (n=6 in each group) which received either anti-Sp35 antibody 1A7, control antibody, or just PBS, by intravitreal injection. The volume of each intravitreal injection was 4 pl while the dosage of each injection was 2 pig. The intravitreal injections were performed immediately after the optic nerve transection. [03991 All animals were allowed to survive for 1 week. Two days before sacrificing the animals, the left optic nerve of each animal was transected and 6% FG was administered as described above to label the surviving RGCs, to serve as the internal control. Animals were sacrificed with an overdose of Nembutal and the retinas dissected in 4% paraformaldehyde. Four radial cuts were made to divide the retinas into four quadrants (superior, inferior, nasal and temporal). The retinas were then post-fixed in the same fixative for 1 hour before they were flat-mounted with the mounting medium (Dako). The slides were examined under a fluorescence microscope using an ultra-violet filter (excitation wavelength = 330-380 nm). Labeled RGCs were counted along the median line of each quadrants starting from the optic disc to the peripheral border of the retina at 500 jim intervals, under an eyepiece grid of 200 X 200 jim 2 . The percentage of surviving RGCs resulting from each treatment was expressed by comparing the number of surviving RGCs in the injured eyes with their contra-lateral - 119 eyes. All data were expressed as mean : SEM. Statistical significance was evaluated by one way ANOVA, followed by a Tukey-Kramer post hoc test. Differences were considered significant for p<0.05. Anti-Sp35 antibody 1A7 treated animals showed more neuronal survival (80%) when compared to control-antibody or PBS treated animals, which each only showed approximately 50% neuronal survival (Fig 6). EXAMPLE 12 Testing Anti-Sp35 antibodies for remyelination in the optic nerve crush model [04001 The right optic nerve receives complete crush by #5 forceps for 10 seconds around 1.5 mm behind the eyeball intraorbitally just before administration of 2 1d of monoclonal antibody 1A7, 2F3, Li05 and Li06 in 2ml by intravitreal injection. [04011 The animals receive a second intravitreal injection of the same treatment one week after the surgery. Two weeks after the surgery, the animals are perfused with EM fixatives, postfixed and processed for semithin and ultrathin sections. The longitudinal optic nerve sections are stained and prepared for myelin observation. The myelination of the proximal and the distal parts of the crushed optic nerve are compared among different treatment groups. Sp35-Fc and 1A7, 2F3, Li05 and Li06 treated animals, as well as appropriate controls, will be analyzed for remyelination in the distal part of the optic nerve compared to the controls. EXAMPLE 13 Testing Anti-Sp35 antibodies for axon regeneration in the optic nerve crush model 104021 The right optic nerve was crushed by #5 forceps for 10 seconds around 1.5-2 mm behind the eyeball intraorbitally just before administration of 2 pg of monoclonal antibody 1A7 in PBS via intravitreal injection. 4 rats were tested with the 1A7 antibody and 8 rats were used as control animals. The animals received a second intravitreal injection of the same treatment one week after the surgery. Three days prior to sacrifice of the test animals (day 11 of the experiment), 2 ml of CTB-FITC was injected intravitreally to label, anterograde, the regenerative optic nerve axons. On the 14th day post sugery, the animals were perfused and postfixed. The crushed optic nerve was processed for frozen longitudinal sections. The CTB-FITC labeled axons, which cross the lesion site were counted as regenerative fibers at various distances beyond the crush site. When 1A7 was injected into the eye, regeneration of axons was observed up to 250 pm beyond the crush site. See Fig. 10.

-120 EXAMPLE 14 Anti-Sp35 antibodies promote remyelination and repair in the optic nerve using the MOG induced EAE rat model. [0403] For theses experiments, the Myelin Oligodendrocyte Glycoprotein (MOG) induced Experimental Autoimmune Encephalomyelitis (EAE) rat model was used. This is the animal model for human multiple sclerosis. 50 pl of 200 ng complete Freund's adjuvant (Chondrex Inc.) plus 50 pLl of 50 pg MOG in saline was emulsified (1:1) and kept on ice before being injected intradermally at the base of the tail for each animal. Female brown Norway rats, 8-10 weeks old, were used for all experiments. General observation in the art indicates that the EAE model is induced around 15 days after MOG injection. Rats are scored for clinical signs of EAE. The signs are scored as follows: grade 0.5, distal paresis of the tail; grade 1, complete tail paralysis; grade 1.5, paresis of the tail and mild hind leg paresis; grade 2.0, unilateral severe hind leg paresis; grade 2.5, bilateral severe hind limb paresis; grade 3.0, complete bilateral hind limb paralysis; grade 3.5, complete bilateral hind limb paralysis and paresis of one front limb; grade complete paralysis (tetraplegia), moribund state, or death. The animals receive treatment once the EAE model is induced. [04041 2pg/pl of an anti-Sp35 antibody (1A7) was injected intravitreally at day 15 upon MOG EAE induction. 2pg/pl of the anti-Sp35 antibody, 1A7, was injected two additional times at day 22 and day 28. Upon termination of the experiment, the animals were perfused with 4% PFA. The optic nerves were post fixed in 1% Os0 4 , dehydrated and embedded in Epon. Semithin sections (1pM) were cut and stained with Toluidine blue for evaluation of myelination. The optic nerves of treated animals were compared to untreated animals for axon regeneration and remyelination in the optic nerve. All procedures were performed following a protocol approved by institutional animal care and use committee (IACUC). [0405] Animals receiving treatment with the anti-Sp35 antibody 1A7 showed remyelination and repair of the optic nerve as compared to normal optic nerves or animals which were subjected to MOG induced EAE, but received no treatment (Fig. 9). In Fig. 9C, the arrows point to myelinated axons. Animals receiving an antibody which recognizes domain II of Protein G from Streptococcus (MOPC21), not specific for Sp35, showed no signs of remylination or repair of the optic nerve as compared to normal optic nerves or the optic nerves of untreated animals (data not shown). The Sp35 antagonist antibody 1A7 promoted remyelination and repair of optic nerves in a rat MOG-induced EAE optic neuritis model (Fig. 9).

- 121 EXAMPLE 15 Testing Anti-Sp35 antibodies for promotion of CNS remyelination using MOG induced EAE mouse model [04061 EAE is induced in the 129B6 mixed strain of mice by intradermal immunization (day 0) with 100 Vg MOG1-125 protein emulsified with complete Freund's adjuvant (CFA). The injected volume is 100 d per mouse and is distributed over 3 sites (pinnae, back and skin). The emulsion is prepared on the basis of a 1:1 volume ratio and contains 1 mg/ml MOG1-125 and 2 mg/ml M. tuberculosis (strain H37Ra, Chondrex). Pertussis toxin (200 ng/mouse) is administered intra peritoneally at the time of immunization and 2 days thereafter. Body weight and clinical EAE scores (0 = no clinical signs; 1 = limp tail; 2 = hind limb weakness, impaired righting reflex or waddled gait; 3 = complete hind limb paralysis or absent righting reflex; 4 = complete hind limb paralysis with some degree of fore limb involvement; 5 = animal fully paralyzed; 6 = moribund or dead) are recorded daily. All procedures are performed following a protocol, approved by our institutional animal care and use committee (IACUC). The animals receive the treatment with 1A7, 2F3, Li05 and Li06 monoclonal anitbodies or control antibody at day 0 of the study. Blood samples are taken at various times throughout the experiments by retro-orbital bleeding technique. Plasma is separated from PBMC by centrifugation and cell phenotyping performed by FACS staining. Profiling of the humoral anti-MOG antibody response is performed by ELISA using subclass-/isotype-specific mAbs (Pharmingen). At the end of each experiment, brain, spinal cord, optic nerves and sciatic nerves are harvested following perfusion. [04071 This same protocol is used to induce the EAE in Sp35 knockout mice and litter mates. Sp35 knockout mice typically show lower EAE score (1.5), and no relapse compared to control (over a 45 day period), then wild type litter mates (EAE score 3.5). 104081 Sp35-Fc and 1A7, 2F3 treated animals will be analyzed for remyelination comparing to the control. [0409] The His-tagged MOG 1s protein was expressed in Pichia pastoris using a Doxycycline inducible TetO-AOX1 promoter (M. Levesque, D. Krushinskie and K. Strauch, manuscript in preparation). The extracellular coding sequence (Glyl through Gly125 of the mature protein after removal of signal sequence) of rat MOG was PCR amplified using the following primers: 5'GGGGTATCTCTCGAGAAAAGAGAGCATCATCATCATCATCATATGGGACAGTTCAGAGT GATAGGG 3' (SEQ ID NO:368), and 5'TTCGCGGCCGCTATTAGCCAGGGTTG ATCCAGTAGAAGGG3' (SEQ ID NO:369).

-122 [04101 The present invention is not to be limited in scope by the specific embodiments described which are intended as single illustrations of individual aspects of the invention, and any compositions or methods which are functionally equivalent are within the scope of this invention. Indeed, various modifications of the invention in addition to those shown and described herein will become apparent to those skilled in the art from the foregoing description and accompanying drawings. Such modifications are intended to fall within the scope of the appended claims. [04111 All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. [04121 The term "comprise" and variants of the term such as "comprises" or "comprising" are used herein to denote the inclusion of a stated integer or stated integers but not to exclude any other integer or any other integers, unless in the context or usage an exclusive interpretation of the term is required. [04131 Any reference to publications cited in this specification is not an admission that the disclosures constitute common general knowledge in Australia.

Claims

1. An isolated antibody or antigen-binding fragment thereof which specifically binds to the same Sp35 epitope as a reference monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3P1D10.2C3, 3P1E1l.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38 DO1 (LiO2), 35-E04 (LiO3), 36-C09 (Li04), 30-Al1 (LiO5), 34-F02 (Li06), 29-E07 (Li07), 34-G04 (LiO8), 36-A12 (LiO9), 28-D02 (LilO), 30-BO1 (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (LIa.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13).

2. An isolated antibody or antigen-binding fragment thereof which specifically binds to Sp35, wherein said antibody or fragment thereof competitively inhibits a reference monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3PID10.2C3, 3PlE11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (Li02), 35-E04 (Li03), 36-C09 (Li04), 30-All (Li05), 34-F02 (Li06), 29-E07 (Li07), 34-G04 (LiO8), 36-A12 (Li09), 28-D02 (LilO), 30-BOl (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lia.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13) from specifically binding to Sp35.

3. An isolated antibody or antigen-binding fragment thereof which specifically binds to Sp35, wherein said antibody or fragment thereof is selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3P1D10.2C3, 3PlEll.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38 DO1 (Li02), 35-E04 (Li03), 36-C09 (LiO4), 30-Al1 (Li05), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (Li08), 36-A12 (Li09), 28-D02 (LilO), 30-BOl (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13).

4. The antibody or fragment thereof of any one of claims 1 to 3, which binds to a linear epitope.

5. The antibody or fragment thereof of any one of claims 1 to 3, which binds to a non-linear conformational epitope.

6. The antibody or fragment thereof of any one of claims 1 to 5, which binds to the Sp35 LRR domain.

7. The antibody or fragment thereof of any one of claims I to 5, which binds to the Sp35 LRRNT or LRRCT domain. -124

8. The antibody or fragment thereof of any one of claims 1 to 5, which binds to the region of Sp35 from amino acids 417-532 of SEQ ID NO:2 or amino acids 495-532 of SEQ ID NO:2.

9. The antibody or fragment thereof of any one of claims 1 to 5, which binds to the Sp35 basic region domain.

10. The antibody of fragment thereof of claim 9 which binds to amino acids 415 to 424 of SEQ ID NO:2 or amino acids 417 to 424 of SEQ ID NO:2.

11. The antibody or fragment thereof of any one of claims 1 to 5, which binds to the Sp35 immunoglobulin domain.

12. The antibody or fragment thereof of claim 11 which binds to amino acids 419 to 493 of SEQ ID NO:2.

13. The antibody or fragment thereof of any one of claims 1 to 5, which binds to the Sp35 LLRCT domain.

14. The antibody of fragment thereof of claim 13 which binds to amino acids 363 to 414 of SEQ ID NO:2 or amino acids 363 to 416 of SEQ ID NO:2.

15. The antibody or fragment thereof of any one of claims 1 to 14, which is a multivalent, and comprises at least two heavy chains and at least two light chains.

16. The antibody or fragment thereof of any one of claims 1 to 15, which is multispecific.

17. The antibody or fragment thereof of claim 16, which is bispecific.

18. The antibody or fragment thereof of any one of claims 1 to 17 which is humanized.

19. The antibody or fragment thereof of any one of claims 1 to 17, which is chimeric.

20. The antibody or fragment thereof of any one of claims 1 to 17, which is primatized.

21. The antibody or fragment thereof of any one of claims 1 to 17, which is fully human.

22. The antibody or fragment thereof of any one of claims 1 to 21, which is an Fab fragment.

23. The antibody or fragment thereof of any one of claims 1 to 21, which is an Fab' fragment.

24. The antibody or fragment thereof of any one of claims 1 to 21, which is an F(ab) 2 fragment.

25. The antibody or fragment thereof of any one of claims 1 to 21, which is an Fv fragment.

26. The antibody or fragment thereof of any one of claims 1 to 21, which is a single chain antibody.

27. The antibody or fragment thereof of any one of claims 1, 2, or 4 to 26, which specifically binds to a Sp35 polypeptide or fragment thereof, or an Sp35 variant polypeptide, with an affinity characterized. by a dissociation constant (KD) which is less than the KD for said reference monoclonal antibody.

28. The antibody or fragment thereof of any one of claims 1 to 26, which specifically binds to a Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide with an affinity characterized by a dissociation constant (KD) no greater than 5 x 102 M, 102 M, 5 x 103 M, 10' - 125 M, 5 x 10~ M, 104 M, 5 x 10~ M, 10- M, 5 x 106 M, 10- M, 5 x 10-7 M, 10~ M, 5 x 10- M, 10' M, 5 x 109 M, 10- M, 5 x 1010 M, 1040 M, 5 x 10" M, 10~" M, 5 x 10-12 M, 10~12 M, 5 x 10-" M, 10~" M, 5 x 10-4 M, 10-4 M, 5 x 10-'- M, or 10-5 M.

29. The antibody or fragment thereof of any one of claims 1 to 28, which preferentially binds to a human Sp35 polypeptide or fragment thereof, relative to a murine Sp35 polypeptide or fragment thereof.

30. The antibody or fragment thereof of any one of claims 1 to 29, which is an antagonist of Sp35 mediated neurite outgrowth inhibition.

31. The antibody or fragment thereof of any one of claims 1 to 29, which is an antagonist of Sp35 mediated neuronal cell death.

32. The antibody or fragment thereof of any one of claims 1 to 29, which is an antagonist of Sp35-mediated myelination inhibition.

33. The antibody or fragment thereof of any one of claims 1 to 29, which is an antagonist of Sp35 mediated oligodendrocyte cell death.

34. The antibody or fragment thereof of any one of claims 1 to 29, which is an antagonist of Sp35 mediated oligodendrocyte differentiation inhibition.

35. The antibody or fragment thereof of any one of claims 1 to 29, which is an antagonist of Sp35 mediated oligodendrocyte proliferation inhibition.

36. The antibody or fragment thereof of any one of claims 1 to 35, further comprising a heterologous polypeptide fused thereto.

37. The antibody or fragment thereof of any one of claims 1 to 36, wherein said antibody is conjugated to an agent selected from the group consisting of a therapeutic agent, a prodrug, a peptide, a protein, an enzyme, a virus, a lipid, a biological response modifier, a pharmaceutical agent, or PEG.

38. A composition comprising the antibody or fragment thereof of any one of claims 1 to 37, and a carrier.

39. An isolated antibody or antigen binding fragment thereof comprising a VH region and a VL region wherein said VH and VL regions comprise, respectively, polypeptide sequences at least 90% identical to the reference polypeptides selected from the group consisting of: i) SEQ ID NO:170 and SEQ ID NO:283; ii) SEQ ID NO:171 and SEQ ID NO:284; iii) SEQ lID NO:172 and SEQ ID NO:285; iv) SEQ ID NO:172 and SEQ ID NO:286; v) SEQ ID NO:158 and SEQ ID NO:273; vi) SEQ ID NO:159 and SEQ ID NO:274; vii) SEQ ID NO:160 and SEQ ID NO:275; - 126 viii) SEQ ID NO:161 and SEQ ID NO:276; ix) SEQ ID NO:163 and SEQ ID NO:277; x) SEQ ID NO:164 and SEQ ID NO:278; xi) SEQ ID NO:165 and SEQ ID NO:279; xii) SEQ ID NO:166 and SEQ ID NO:280; xiii) SEQ ID NO:167 and SEQ ID NO:281; xiv) SEQ ID NO:168 and SEQ ID NO:282; xv) SEQ ID NO:372 and SEQ ID NO:373; xvi) SEQ ID NO:376 and SEQ ID NO:377; xvii) SEQ ID NO:380 and SEQ ID NO:381; and xviii) SEQ ID NO:384 and SEQ ID NO:385; and wherein an antibody or antigen-binding fragment thereof comprising said VH and VL specifically binds to Sp35.

40. An isolated antibody or antigen binding fragment thereof comprising a VH region and a VL region wherein said VH and VL regions, respectively, are identical, except for less than 20 conservative amino acid substitutions, to reference polypeptides selected from the group consisting of: i) SEQ ID NO:170 and SEQ ID NO:283; ii) SEQ ID NO:171 and SEQ ID NO:284; iii) SEQ ID NO: 172 and SEQ ID NO:285; iv) SEQ ID NO: 172 and SEQ ID NO:286; v) SEQ ID NO:158 and SEQ ID NO:273; vi) SEQ ID NO:159 and SEQ ID NO:274; vii) SEQ ID NO:160 and SEQ ID NO:275; viii) SEQ ID NO:161 and SEQ ID NO:276; ix) SEQ ID NO:163 and SEQ ID NO:277; x) SEQ ID NO:164 and SEQ ID NO:278; xi) SEQ ID NO:165 and SEQ ID NO:279; xii) SEQ ID NO:166 and SEQ ID NO:280; xiii) SEQ ID NO:167 and SEQ ID NO:281; xiv) SEQ ID NO:168 and SEQ ID NO:282; xv) SEQ ID NO:372 and SEQ ID NO:373; xvi) SEQ ID NO:376 and SEQ ID NO:377; xvii) SEQ ID NO:380 and SEQ ID NO:381; and xviii) SEQ ID NO:384 and SEQ ID NO:385 - 127 and wherein an antibody or antigen-binding fragment thereof comprising said VH and VL specifically binds to Sp35.

41. An isolated antibody or antigen binding fragment thereof comprising a VH region and a VL region wherein said VH and VL regions comprise, respectively, polypeptides selected from the group consisting of: i) SEQ ID NO:170 and SEQ ID NO:283; ii) SEQ ID NO:171 and SEQ ID NO:284; iii) SEQ ID NO: 172 and SEQ ID NO:285; iv) SEQ ID NO:172 and SEQ ID NO:286; v) SEQ ID NO:158 and SEQ ID NO:273; vi) SEQ ID NO:159 and SEQ ID NO:274; vii) SEQ ID NO:160 and SEQ ID NO:275; viii) SEQ ID NO:161 and SEQ ID NO:276; ix) SEQ ID NO:163 and SEQ ID NO:277; x) SEQ ID NO:164 and SEQ ID NO:278; xi) SEQ ID NO:165 and SEQ ID NO:279; xii) SEQ ID NO:166 and SEQ ID NO:280; xiii) SEQ ID NO:167 and SEQ ID NO:281; xiv) SEQ ID NO:168 and SEQ ID NO:282; xv) SEQ ID NO:372 and SEQ ID NO:373; xvi) SEQ ID NO:376 and SEQ ID NO:377; xvii) SEQ ID NO:380 and SEQ ID NO:381; and xviii) SEQ ID NO:384 and SEQ ID NO:385.

42. An isolated polynucleotide comprising a nucleic acid encoding an immunoglobulin heavy chain variable region (VH), wherein the CDR1, CDR2, and CDR3 regions of said VH are at least 90% identical, respectively, to reference heavy chain CDR1, CDR2, and CDR3 polypeptide sequences selected from the group consisting of: a) SEQ ID NO:6, SEQ ID NO:8, and SEQ ID NO:10, b) SEQ ID NO:12, SEQ ID NO:14, and SEQ ID NO:16, c) SEQ ID NO: 18, SEQ ID NO:20, and SEQ ID NO:22, d) SEQ ID NO:24, SEQ ID NO:26, and SEQ ID NO:28, e) SEQ ID NO:30, SEQ ID NO:32, and SEQ ID NO:34, f) SEQ ID NO:36, SEQ ID NO:38, and SEQ ID NO:40, g) SEQ ID NO:42, SEQ ID NO:44, and SEQ ID NO:46, h) SEQ ID NO:48, SEQ ID NO:50, and SEQ ID NO:52, i) SEQ ID NO:54, SEQ ID NO:56, and SEQ ID NO:58, - 128 j) SEQ ID NO:60, SEQ ID NO:61, and SEQ ID NO:62, k) SEQ ID NO:64, SEQ ID NO:66, and SEQ ID NO:68, 1) SEQ ID NO:66, SEQ ID NO:68, and SEQ ID NO:70, m) SEQ ID NO:72, SEQ ID NO:74, and SEQ ID NO:76, n) SEQ ID NO:77, SEQ ID NO:78, and SEQ ID NO:79, o) SEQ ID NO:80, SEQ ID NO:81, and SEQ ID NO:82, p) SEQ ID NO:83, SEQ ID NO:84, and SEQ ID NO:85; q) SEQ ID NO:195 SEQ ID NO:196 and SEQ ID NO:197; r) SEQ ID NO:198 SEQ ID NO:199 and SEQ ID NO:200; s) SEQ ID NO:201 SEQ ID NO:202 and SEQ ID NO:203; t) SEQ ID NO:204 SEQ ID NO:205 and SEQ ID NO:206; u) SEQ ID NO:207 SEQ ID NO:208 and SEQ ID NO:209; v) SEQ ID NO:210 SEQ ID NO:211 and SEQ ID NO:212; w) SEQ ID NO:213 SEQ ID NO:214 and SEQ ID NO:215; x) SEQ ID NO:216 SEQ ID NO:217 and SEQ ID NO:218; y) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; z) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; aa) SEQ ID NO:222 SEQ ID NO:223 and SEQ ID NO:224; bb) SEQ ID NO:225 SEQ ID NO:226 and SEQ ID NO:227; cc) SEQ ID NO:228 SEQ ID NO:229 and SEQ ID NO:230; dd) SEQ ID NO:231 SEQ ID NO:232 and SEQ ID NO:233; ee) SEQ ID NO:389 SEQ ID NO:390 and SEQ ID NO:391; ff) SEQ ID NO:395 SEQ ID NO:396 and SEQ ID NO:397; gg) SEQ ID NO:401 SEQ ID NO:402 and SEQ ID NO:403; and hh) SEQ ID NO:407 SEQ ID NO:408 and SEQ ID NO:409; and wherein an antibody or antigen-binding fragment thereof comprising said VH specifically binds to Sp35.

43. An isolated polynucleotide comprising a nucleic acid encoding an immunoglobulin heavy chain variable region (VH), wherein the CDR1, CDR2, and CDR3 regions of said VH are identical respectively, except for less than 20 conservative amino acid substitutions, to reference heavy chain CDRI, CDR2, and CDR3 sequences selected from the group consisting of: a) SEQ ID NO:6, SEQ ID NO:8, and SEQ ID NO:10, b) SEQ ID NO:12, SEQ ID NO:14, and SEQ ID NO:16, c) SEQ ID NO:18, SEQ ID NO:20, and SEQ ID NO:22, d) SEQ ID NO:24, SEQ ID NO:26, and SEQ ID NO:28, e) SEQ ID NO:30, SEQ ID NO:32, and SEQ ID NO:34, -129 f) SEQ ID NO:36, SEQ ID NO:38, and SEQ ID NO:40, g) SEQ ID NO:42, SEQ ID NO:44, and SEQ ID NO:46, h) SEQ ID NO:48, SEQ ID NO:50, and SEQ ID NO:52, i) SEQ ID NO:54, SEQ ID NO:56, and SEQ ID NO:58, j) SEQ ID NO:60, SEQ ID NO:61, and SEQ ID NO:62, k) SEQ ID NO:64, SEQ ID NO:66, and SEQ ID NO:68, 1) SEQ ID NO:66, SEQ ID NO:68, and SEQ ID NO:70, m) SEQ ID NO:72, SEQ ID NO:74, and SEQ ID NO:76, n) SEQ ID NO:77, SEQ ID NO:78, and SEQ ID NO:79, o) SEQ ID NO:80, SEQ ID NO:81, and SEQ ID NO:82, p) SEQ ID NO:83, SEQ ID NO:84, and SEQ ID NO:85; q) SEQ ID NO:195 SEQ ID NO:196 and SEQ ID NO:197; r) SEQ ID NO:198 SEQ ID NO:199 and SEQ ID NO:200; s) SEQ ID NO:201 SEQ lID NO:202 and SEQ ID NO:203; t) SEQ ID NO:204 SEQ ID NO:205 and SEQ ID NO:206; u) SEQ ID NO:207 SEQ ID NO:208 and SEQ ID NO:209; v) SEQ ID NO:210 SEQ ID NO:211 and SEQ ID NO:212; w) SEQ ID NO:213 SEQ ID NO:214 and SEQ ID NO: 2 15 ; x) SEQ ID NO:216 SEQ ID NO:217 and SEQ ID NO:218; y) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; z) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; aa) SEQ ID NO:222 SEQ ID NO:223 and SEQ ID NO:224; bb) SEQ ID NO:225 SEQ ID NO:226 and SEQ ID NO:227; cc) SEQ ID NO:228 SEQ ID NO:229 and SEQ ID NO:230; dd) SEQ ID NO:231 SEQ ID NO:232 and SEQ ID NO:233; ee) SEQ ID NO:389 SEQ ID NO:390 and SEQ ID NO:391; ff) SEQ ID NO:395 SEQ ID NO:396 and SEQ ID NO:397; gg) SEQ ID NO:401 SEQ ID NO:402 and SEQ ID NO:403; and hh) SEQ ID NO:407 SEQ ID NO:408 and SEQ ID NO:409; and wherein an antibody or antigen-binding fragment thereof comprising said VII specifically binds to Sp35.

44. The polynucleotide of any one of claims 42 or 43, wherein the CDR1, CDR2, and CDR3 regions of said VH comprise polypeptide sequences selected from the group consisting of: a) SEQ ID NO:6, SEQ ID NO:8, and SEQ ID NO:10, b) SEQ ID NO:12, SEQ ID NO:14, and SEQ ID NO:16, c) SEQ ID NO:18, SEQ ID NO:20, and SEQ ID NO:22, - 130 d) SEQ ID NO:24, SEQ ID NO:26, and SEQ ID NO:28, e) SEQ ID NO:30, SEQ ID NO:32, and SEQ ID NO:34, f) SEQ ID NO:36, SEQ ID NO:38, and SEQ ID NO:40, g) SEQ ID NO:42, SEQ ID NO:44, and SEQ ID NO:46, h) SEQ ID NO:48, SEQ ID NO:50, and SEQ ID NO:52, i) SEQ ID NO:54, SEQ ID NO:56, and SEQ ID NO:58, j) SEQ ID NO:60, SEQ ID NO:61, and SEQ ID NO:62, k) SEQ ID NO:64, SEQ ID NO:66, and SEQ ID NO:68, 1) SEQ ID NO:66, SEQ ID NO:68, and SEQ ID NO:70, m) SEQ ID NO:72, SEQ ID NO:74, and SEQ ID NO:76, n) SEQ ID NO:77, SEQ ID NO:78, and SEQ ID NO:79, o) SEQ ID NO:80, SEQ ID NO:81, and SEQ ID NO:82, p) SEQ ID NO:83, SEQ ID NO:84, and SEQ ID NO:85; q) SEQ ID NO:195 SEQ ID NO:196 and SEQ ID NO:197; r) SEQ ID NO:198 SEQ ID NO:199 and SEQ ID NO:200; s) SEQ ID NO:201 SEQ ID NO:202 and SEQ ID NO:203; t) SEQ ID NO:204 SEQ ID NO:205 and SEQ ID NO:206; u) SEQ ID NO:207 SEQ ID NO:208 and SEQ ID NO:209; v) SEQ ID NO:210 SEQ ID NO:211 and SEQ ID NO:212; w) SEQ ID NO:213 SEQ ID NO:214 and SEQ ID NO:215; x) SEQ ID NO:216 SEQ ID NO:217 and SEQ ID NO:218; y) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; z) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; aa) SEQ ID NO:222 SEQ ID NO:223 and SEQ ID NO:224; bb) SEQ ID NO:225 SEQ ID NO:226 and SEQ ID NO:227; cc) SEQ ID NO:228 SEQ ID NO:229 and SEQ ID NO:230; dd) SEQ ID NO:231 SEQ ID NO:232 and SEQ ID NO:233; ee) SEQ ID NO:389 SEQ ID NO:390 and SEQ ID NO:391; ff) SEQ ID NO:395 SEQ ID NO:396 and SEQ ID NO:397; gg) SEQ ID NO:401 SEQ ID NO:402 and SEQ ID NO:403; and hh) SEQ ID NO:407 SEQ ID NO:408 and SEQ ID NO:409.

45. An isolated polynucleotide comprising a nucleic acid encoding an immunoglobulin heavy chain (VII), wherein said CDR1, CDR2, and CDR3 regions of said VH are encoded by nucleic acid sequences selected from the group consisting of: a) SEQ ID NO:5, SEQ ID NO:7, and SEQ ID NO:9, b) SEQ ID NO:11, SEQ ID NO:13, and SEQ ID NO:15, -131 c) SEQ ID NO:17, SEQ ID NO:19, and SEQ ID NO:21, d) SEQ ID NO:23, SEQ ID NO:25, and SEQ ID NO:27, e) SEQ ID NO:29, SEQ ID NO:31, and SEQ ID NO:33, f) SEQ ID NO:35, SEQ ID NO:37, and SEQ ID NO:39, g) SEQ ID NO:41, SEQ ID NO:43, and SEQ ID NO:45, h) SEQ ID NO:47, SEQ ID NO:49, and SEQ ID NO:51, i) SEQ ID NO:53, SEQ ID NO:55, and SEQ ID NO:57, j) SEQ ID NO:59, SEQ ID NO:61, and SEQ ID NO:63, k) SEQ ID NO:65, SEQ ID NO:67, and SEQ ID NO:69, and 1) SEQ ID NO:71, SEQ ID NO:73, and SEQ ID NO:75.

46. An isolated polynucleotide comprising a nucleic acid encoding a VH region at least 90% identical to a reference VH polypeptide sequence selected from the group consisting of SEQ ID NOs: 158 to 172, 372, 376, 380 and 384, wherein an antibody or antigen-binding fragment thereof comprising said VH specifically binds to Sp35.

47. An isolated polynucleotide comprising a nucleic acid encoding a VH region identical to a reference VH polypeptide sequence selected from the group consisting of SEQ ID NOs: 158 to 172, 372, 376, 380 and 384, except for less than 20 conservative amino acid substitutions, and wherein an antibody or antigen-binding fragment thereof comprising said VH specifically binds to Sp 35 .

48. The polynucleotide of any one of claims 46 or 47, wherein said VH is identical to said reference VH.

49. The polynucleotide of any one of claims 46 or 47, wherein said VH is encoded by a nucleic acid sequence selected from the group consisting of SEQ ID NOs:173 to 184, 370, 374, 378 and 382.

50. The polynucleotide of any one of claims 42 to 49, further comprising a nucleic acid encoding a signal peptide fused to said VH.

51. The polynucleotide of any one of claims 42 to 49, further comprising a nucleic acid encoding a CH1 domain fused to said VH.

52. The polynucleotide of any one of claims 42 to 49, further comprising a nucleic acid encoding a CH2 domain fused to said VH.

53. The polynucleotide of any one of claims 42 to 49, further comprising a nucleic acid encoding a CH3 domain fused to said VH.

54. The polynucleotide of any one of claims 42 to 49, further comprising a nucleic acid encoding the hinge region fused to said VH.

55. The polynucleotide of any one of claims 42 to 54, wherein an antibody or antigen-binding fragment thereof comprising said VH specifically binds to the same epitope as a monoclonal -132 antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3PID10.2C3, 3PlE11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (LiO2), 35-E04 (Li03), 36-C09 (Li04), 30-Al1 (Li05), 34-F02 (Li06), 29-E07 (Li07), 34-G04 (Li08), 36-A12 (Li09), 28-D02 (LilO), 30-BOl (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13).

56. The polynucleotide of any one of claims 42 to 54, wherein an antibody or antigen-binding fragment thereof comprising said VH competitively inhibits a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3P1D10.2C3, 3PIE11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (Li02), 35-E04 (Li03), 36-C09 (Li04), 30-Al1 (Li05), 34-F02 (Li06), 29 E07 (Li07), 34-G04 (Li08), 36-A12 (Li09), 28-D02 (LilO), 30-BO1 (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13) from binding to Sp35.

57. The polynucleotide of any one of claims 42 to 54, wherein an antibody or antigen-binding fragment thereof comprising said VH specifically binds to a Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no greater than 5 x 102 M, 10- M, 5 x 10- M, 10- M, 5 x 10-4 M, 1 0 -4 M, 5 x 10- M, 10- M, 5 x 10-6 M, 10-6 M, 5 x 104 M, 10-7 M, 5 x 10" M, 10- M, 5 x 10-9 M, 10-9 M, 5 x 1010 M, 10-1 M, 5 x 10 " M, 10~" M, 5 x 10-12 M, 10-12 M, 5 x 10-" M, 10~ 3 M, 5 x 10-4 M, 10- 4 M, 5 x 10-" M, or 104" M.

58. An isolated polynucleotide comprising a nucleic acid encoding an immunoglobulin light chain variable region (VL), wherein the CDRI, CDR2, and CDR3 regions of said VL are at least 90% identical, respectively, to reference light chain CDRI, CDR2, and CDR3 sequences selected from the group consisting of: a) SEQ ID NO:87, SEQ ID NO:89, and SEQ ID NO:91; b) SEQ ID NO:93, SEQ ID NO:95, and SEQ ID NO:97; c) SEQ ID NO:99, SEQ ID NO:101, and SEQ ID NO:103; d) SEQ ID NO: 105, SEQ ID NO:107, and SEQ ID NO:109; e) SEQ ID NO:111, SEQ ID NO:113, and SEQ ID NO:115; f) SEQ ID NO:117, SEQ ID NO:119, and SEQ ID NO:121; g) SEQ ID NO:123, SEQ ID NO:125, and SEQ ID NO:127; h) SEQ ID NO:129, SEQ ID NO:131, and SEQ ID NO:133; i) SEQ ID NO:135, SEQ ID NO:137, and SEQ ID NO:139; - 133 j) SEQ ID NO:141, SEQ ID NO:143, and SEQ ID NO:145; k) SEQ ID NO:146, SEQ ID NO:147, and SEQ ID NO:148; 1) SEQ ID NO:149, SEQ ID NO:150, and SEQ ID NO:151; m) SEQ IDNO:152, SEQ IDNO:153, and SEQ ID NO:154; n) SEQ ID NO:155, SEQ ID NO:156, and SEQ ID NO:157; o) SEQ ID NO:234, SEQ ID NO:235, and SEQ ID NO:236, p) SEQ ID NO:237, SEQ ID NO:238, and SEQ ID NO:239; q) SEQ ID NO:240, SEQ ID NO:241, and SEQ ID NO:242; r) SEQ ID NO:243, SEQ ID NO:244, and SEQ ID NO:245; s) SEQ ID NO:246, SEQ ID NO:247, and SEQ ID NO:248; t) SEQ ID NO:249, SEQ ID NO:250, and SEQ ID NO:251; u) SEQ ID NO:252, SEQ ID NO:253, and SEQ ID NO:254; v) SEQ ID NO:255, SEQ ID NO:256, and SEQ ID NO:257; w) SEQ ID NO:258, SEQ ID NO:259, and SEQ ID NO:260; x) SEQ ID NO:261, SEQ ID NO:262, and SEQ ID NO:263; y) SEQ ID NO:264, SEQ lID NO:265, and SEQ ID NO:266; z) SEQ ID NO:267, SEQ ID NO:268, and SEQ ID NO:269; aa) SEQ ID NO:270, SEQ ID NO:271, and SEQ ID NO:272; bb) SEQ ID NO:386, SEQ ID NO:387, and SEQ ID NO:388; cc) SEQ ID NO:392, SEQ ID NO:393, and SEQ ID NO:394; dd) SEQ ID NO:398, SEQ ID NO:399, and SEQ ID NO:400; and ee) SEQ ID NO:404, SEQ ID NO:405, and SEQ ID NO:406; and wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to Sp35.

59. An isolated polynucleotide comprising a nucleic acid encoding an immunoglobulin light chain variable region (VL), wherein the CDR1, CDR2, and CDR3 regions of said VL are identical respectively, except for less than 20 conservative amino acid substitutions, to reference light chain CDR1, CDR2, and CDR3 sequences selected from the group consisting of: a) SEQ ID NO:87, SEQ ID NO:89, and SEQ ID NO:91; b) SEQ ID NO:93, SEQ ID NO:95, and SEQ ID NO:97; c) SEQ ID NO:99, SEQ ID NO:101, and SEQ ID NO:103; d) SEQ ID NO:105, SEQ ID NO:107, and SEQ ID NO:109; e) SEQ ID NO:111, SEQ ID NO:113, and SEQ ID NO:115; f) SEQ ID NO:117, SEQ ID NO:119, and SEQ ID NO:121; g) SEQ ID NO:123, SEQ ID NO:125, and SEQ ID NO:127; h) SEQ ID NO:129, SEQ ID NO:131, and SEQ ID NO:133; -134 i) SEQ ID NO:135, SEQ ID NO:137, and SEQ ID NO:139; j) SEQ ID NO:141, SEQ ID NO:143, and SEQ ID NO:145; k) SEQ ID NO:146, SEQ ID NO:147, and SEQ ID NO:148; 1) SEQ IDNO:149, SEQ IDNO:150, and SEQ IDNO:151; m) SEQ ID NO:152, SEQ ID NO:15 3 , and SEQ IDNO:154; n) SEQ ID NO:155, SEQ ID NO:156, and SEQ ID NO:157; o) SEQ ID NO:234, SEQ ID NO:235, and SEQ ID NO:236, p) SEQ ID NO:237, SEQ ID NO:238, and SEQ ID NO:239; q) SEQ ID NO:240, SEQ ID NO:241, and SEQ ID NO:242; r) SEQ ID NO:243, SEQ ID NO:244, and SEQ ID NO:245; s) SEQ ID NO:246, SEQ ID NO:247, and SEQ ID NO:248; t) SEQ ID NO:249, SEQ ID NO:250, and SEQ ID NO:25 1; u) SEQ ID NO:252, SEQ ID NO:253, and SEQ ID NO:254; v) SEQ ID NO:255, SEQ ID NO:256, and SEQ ID NO:257; w) SEQ ID NO:258, SEQ ID NO:259, and SEQ ID NO:260; x) SEQ ID NO:261, SEQ ID NO:262, and SEQ ID NO:263; y) SEQ ID NO:264, SEQ ID NO:265, and SEQ ID NO:266; z) SEQ ID NO:267, SEQ ID NO:268, and SEQ ID NO:269; aa) SEQ ID NO:270, SEQ ID NO:271, and SEQ ID NO:272; bb) SEQ ID NO:386, SEQ ID NO:387, and SEQ ID NO:388; cc) SEQ ID NO:392, SEQ ID NO:393, and SEQ ID NO:394; dd) SEQ ID NO:398, SEQ ID NO:399, and SEQ ID NO:400; and ee) SEQ ID NO:404, SEQ ID NO:405, and SEQ ID NO:406; and wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to Sp35.

60. The polynucleotide of any one of claims 58 or 59, wherein the CDRI, CDR2, and CDR3 regions of said VL comprise polypeptides sequences selected from the group consisting of: a) SEQ ID NO:87, SEQ ID NO:89, and SEQ ID NO:91; b) SEQ ID NO:93, SEQ ID NO:95, and SEQ ID NO:97; c) SEQ ID NO:99, SEQ ID NO:101, and SEQ ID NO:103; d) SEQ ID NO:105, SEQ ID NO:107, and SEQ ID NO:109; e) SEQ ID NO:111, SEQ ID NO:113, and SEQ ID NO:115; f) SEQ ID NO:117, SEQ ID NO:119, and SEQ ID NO: 12 1 ; g) SEQ ID NO:123, SEQ ID NO:125, and SEQ ID NO:127; h) SEQ ID NO:129, SEQ ID NO:131, and SEQ ID NO:133; i) SEQ ID NO:135, SEQ ID NO:137, and SEQ ID NO:139; - 135 j) SEQ ID NO:141, SEQ ID NO:143, and SEQ ID NO:145; k) SEQ ID NO:146, SEQ ID NO: 147, and SEQ ID NO:148; 1) SEQ ID NO:149, SEQ ID NO:150, and SEQ ED NO:151; m) SEQIDNO:152, SEQIDNO:153, and SEQ IDNO:154; n) SEQ ID NO:155, SEQ ID NO:156, and SEQ ID NO:157; o) SEQ ID NO:234, SEQ ID NO:235, and SEQ ID NO:236, p) SEQ ID NO:237, SEQ ID NO:238, and SEQ ID NO:239; q) SEQ ID NO:240, SEQ ID NO:241, and SEQ ID NO:242; r) SEQ ID NO:243, SEQ ID NO:244, and SEQ ID NO:245; s) SEQ ID NO:246, SEQ ID NO:247, and SEQ ID NO:248; t) SEQ ID NO:249, SEQ ID NO:250, and SEQ ID NO:251; u) SEQ ID NO:252, SEQ ID NO:253, and SEQ ID NO:254; v) SEQ ID NO:255, SEQ ID NO:256, and SEQ ID NO:257; w) SEQ ID NO:258, SEQ ID NO:259, and SEQ ID NO:260; x) SEQ ID NO:261, SEQ ID NO:262, and SEQ ID NO:263; y) SEQ ID NO:264, SEQ ID NO:265, and SEQ ID NO:266; z) SEQ ID NO:267, SEQ ID NO:268, and SEQ ID NO:269; aa) SEQ ID NO:270, SEQ ID NO:271, and SEQ ID NO:272; bb) SEQ ID NO:386, SEQ ID NO:387, and SEQ ID NO:388; cc) SEQ ID NO:392, SEQ ID NO:393, and SEQ ID NO:394; dd) SEQ ID NO:398, SEQ ID NO:399, and SEQ ID NO:400; and ee) SEQ ID NO:404, SEQ ID NO:405, and SEQ ID NO:406.

61. An isolated polynucleotide comprising a nucleic acid encoding an immunoglobulin light chain variable region (VL), wherein said CDRI, CDR2, and CDR3 regions of said VL are encoded by a nucleic acid sequence selected from the group consisting of: a) SEQ ID NO:86, SEQ ID NO:88, and SEQ ID NO:90, b) SEQ ID NO:92, SEQ ID NO:94, and SEQ ID NO:96, c) SEQ ID NO:98, SEQ ID NO:100, and SEQ ID NO:102, d) SEQ ID NO:104, SEQ ID NO:106, and SEQ ID NO:108, e) SEQ ID NO:110, SEQ ID NO:112, and SEQ ID NO:114, f) SEQ ID NO:116, SEQ ID NO:118, and SEQ ID NO:120, g) SEQ ID NO:122, SEQ ID NO:124, and SEQ ID NO:126, h) SEQ ID NO:128, SEQ ID NO:130, and SEQ ID NO: 132, i) SEQ ID NO:134, SEQ ID NO:136, and SEQ ID NO:138, and j) SEQ ID NO: 140, SEQ ID NO: 142, and SEQ ID NO: 144. -136

62. An isolated polynucleotide comprising a nucleic acid encoding a VL region at least 90% identical to a reference VL polypeptide sequence selected from the group consisting of SEQ ID NOs: 273 to 286, 373, 377, 381 and 385, wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to Sp35.

63. An isolated polynucleotide comprising a nucleic acid encoding a VL region identical to a reference VL polypeptide sequence selected from the group consisting of SEQ ID NOs: 273 to 286, 373, 377, 381 and 385, except for less than 20 conservative amino acid substitutions, and wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to Sp35.

64. The polynucleotide of any one of claims 62 or 63, wherein said VL is identical to said reference VL.

65. The polynucleotide of claim 64, wherein said VL is encoded by a nucleic acid sequence selected from the group consisting of SEQ ID NOs: 185 to 194, 371, 375, 379, and 383.

66. The polynucleotide of any one of claims 58 to 65, further comprising a nucleic acid encoding a signal peptide fused to said VL.

67. The polynucleotide of any one of claims 58 to 65, further comprising a nucleic acid encoding a CH1 domain fused to said VL.

68. The polynucleotide of any one of claims 58 to 65, further comprising a nucleic acid encoding a CH2 domain fused to said VL.

69. The polynucleotide of any one of claims 58 to 65, further comprising a nucleic acid encoding a CH3 domain fused to said VL.

70. The polynucleotide of any one of claims 58 to 65, further comprising a nucleic acid encoding the hinge region fused to said VL.

71. The polynucleotide of any one of claims 58 to 70, wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to the same epitope as a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3PlD1O.2C3, 3P1E11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (Li02), 35-E04 (Li03), 36-C09 (LiO4), 30-Al1 (Li05), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (LiO8), 36-A12 (Li09), 28-D02 (LilO), 30-BO1 (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.1 1), 3582 (Lla.12), and 1968 (Lla.13).

72. The polynucleotide of any one of claims 58 to 70, wherein an antibody or antigen-binding fragment thereof comprising said VL competitively inhibits a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3PID10.2C3, 3PIE11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, - 137 30-C12 (LiOl), 38-DO 1 (LiO2), 35-E04 (Li03), 36-C09 (LiO4), 30-Al1 (Li05), 34-F02 (Li06), 29 E07 (Li07), 34-G04 (Li08), 36-A12 (Li09), 28-D02 (LilO), 30-BO (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13) from binding to Sp35.

73. The polynucleotide of any one of claims 58 to 72, wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to a Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no greater than 5 x 10"2 M, 102 M, 5 x 10-' M, 10-' M, 5 x 1 0 ~4 M, 1 0 -4 M, 5 x 10~' M, 10- M, 5 x 10-6 M, 10-6 M, 5 x 10- M, 10~7 M, 5 x 10- M, 10- M, 5 x 10-9 M, 109 M, 5 x 1010 M, 10-W M, 5 x 10~ " M, 10" M, 5 x 10-12 M, 102 M, 5 x 10~" M, 10-4 M, 5 x 10-44 M, 10-4 M, 5 x 10-" M, or 10~" M.

74. The polynucleotide of any one of claims 42 to 73, further comprising a heterologous polynucleotide.

75. The polynucleotide of claim 74, wherein said heterologous polynucleotide encodes a heterologous polypeptide.

76. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL specifically binds to a linear epitope.

77. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL specifically binds to a non-linear conformational epitope.

78. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL specifically binds to the Sp35 LRR domain.

79. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL specifically binds to the Sp35 LRRNT domain.

80. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL specifically binds to the Sp35 LRRCT domain.

81. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL specifically binds to the Sp35 immunoglobulin domain.

82. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL specifically binds to the Sp35 basic region.

83. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is a multivalent antibody molecule comprising at least two heavy chains and at least two light chains. - 138 84. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is multispecific.

85. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is bispecific.

86. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is monovalent, bivalent, polyvalent, or bifunctional.

87. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is humanized.

88. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is chimeric.

89. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is primatized.

90. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is fully human.

91. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is an Fab fragment.

92. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is an Fab' fragment.

93. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is an F(ab) 2 fragment.

94. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is an Fv fragment.

95. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is a single chain antibody.

96. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL specifically binds to a Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide with an affinity characterized by a dissociation constant (KD) no greater than 5 x 102 M, 102 M, 5 x 104 M, 10' M, 5 x 1 0 -4 M, 1 0 -4 M, 5 x 10-' M, 10-' M 5 x 10- M, 106 M, 5 x 10- 7 M, 10- 7 M, 5 x 108 M, 108 M, 5 x 10~ 9 M, 10- 9 M, 5 x 10 10 M, 1040 M, 5 x 10~" M, 10~" M, 5 x 1012 M, 1012 M, 5 x 10-' M, 10~1 M, 5 x 10-4 M, 10-" M, 5 x 10-5 M, or 10-1 M.

97. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL preferentially binds to a human Sp35 polypeptide or fragment thereof, relative to a murine Sp35 polypeptide or fragment thereof. -139

98. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is an antagonist of Sp 3 5 mediated neurite outgrowth inhibition.

99. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is an antagonist of Sp35-mediated myelination inhibition.

100. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is an antagonist of Sp35 mediated oligodendrocyte cell death.

101. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is an antagonist of Sp 3 5 mediated oligodendrocyte differentiation inhibition.

102. The polynucleotide of any one of claims 42 to 75, wherein an antibody or antigen-binding fragment thereof comprising said VH or said VL is an antagonist of Sp35 mediated oligodendrocyte proliferation inhibition.

103. A composition comprising the polynucleotide of any one of claims 42 to 102.

104. A composition comprising a VH encoding polynucleotide and a VL encoding polynucleotide, wherein said VH encoding polynucleotide and said VL encoding polynucleotide, respectively, comprise polynucleotides encoding amino acid sequences at least 90% identical to the reference polypeptides selected from the group consisting of: i) SEQ ID NO: 170 and SEQ ID NO:283; ii) SEQ ID NO:171 and SEQ ID NO:284; iii) SEQ ID NO: 172 and SEQ ID NO:285; iv) SEQ ID NO:172 and SEQ ID NO:286; v) SEQ ID NO:158 and SEQ ID NO:273; vi) SEQ ID NO:159 and SEQ ID NO:274; vii) SEQ ID NO:160 and SEQ ID NO:275; viii) SEQ ID NO:161 and SEQ ID NO:276; ix) SEQ ID NO:163 and SEQ ID NO:277; x) SEQ ID NO:164 and SEQ ID NO:278; xi) SEQ ID NO:165 and SEQ ID NO:279; xii) SEQ ID NO: 166 and SEQ ID NO:280; xiii) SEQ ID NO:167 and SEQ ID NO:281; xiv) SEQ ID NO:168 and SEQ ID NO:282; xv) SEQ ID NO:372 and SEQ ID NO:373; xvi) SEQ ID NO:376 and SEQ UD NO:377; -140 xvii) SEQ ID NO:380 and SEQ ID NO:381; and xviii) SEQ ID NO:384 and SEQ ID NO:385; and wherein said VH and VL encoding polynucleotides together encode an antibody or binding fragment thereof which specifically binds Sp35.

105. A composition comprising a VH encoding polynucleotide and a VL encoding polynucleotide, wherein said VH encoding polynucleotide and said VL encoding polynucleotide, respectively, comprise polynucleotides encoding amino acid sequences identical, except for less than 20 conservative amino acid substitutions, to the reference polypeptides selected from the group consisting of: i) SEQ ID NO:170 and SEQ ID NO:283; ii) SEQ ID NO:171 and SEQ ID NO:284; iii) SEQ ID NO:172 and SEQ ID NO:285; iv) SEQ ID NO:172 and SEQ ID NO:286; v) SEQ ID NO:158 and SEQ ID NO:273; vi) SEQ ID NO:159 and SEQ ID NO:274; vii) SEQ ID NO:160 and SEQ ID NO:275; viii) SEQ ID NO:161 and SEQ ID NO:276; ix) SEQ ID NO:163 and SEQ ID NO:277; x) SEQ ID NO:164 and SEQ ID NO:278; xi) SEQ ID NO:165 and SEQ DD NO:279; xii) SEQ ID NO:166 and SEQ ID NO:280; xiii) SEQ ID NO:167 and SEQ ID NO:281; xiv) SEQ ID NO:168 and SEQ ID NO:282; xv) SEQ ID NO:372 and SEQ ID NO:373; xvi) SEQ ID NO:376 and SEQ ID NO:377; xvii) SEQ ID NO:380 and SEQ ID NO:381; and xviii) SEQ ID NO:384 and SEQ ID NO:385; and wherein said VH and VL encoding polynucleotides together encode an antibody or binding fragment thereof which specifically binds Sp35.

106. A composition comprising a VH encoding polynucleotide and a VL encoding polynucleotide, wherein said VH encoding polynucleotide and said VL encoding polynucleotide, respectively, comprise polynucleotides encoding amino acid sequences identical to the reference polypeptides selected from the group consisting of: i) SEQ ID NO:170 and SEQ ID NO:283; ii) SEQ ID NO:171 and SEQ ID NO:284; -141 iii) SEQ ID NO:172 and SEQ ID NO:285; iv) SEQ ID NO:172 and SEQ ID NO:286; v) SEQ ID NO:158 and SEQ ID NO:273; vi) SEQ ID NO:159 and SEQ ID NO:274; vii) SEQ ID NO:160 and SEQ ID NO:275; viii) SEQ ID NO:161 and SEQ ID NO:276; ix) SEQ ID NO:163 and SEQ ID NO:277; x) SEQ ID NO:164 and SEQ ID NO:278; xi) SEQ ID NO:165 and SEQ ID NO:279; xii) SEQ ID NO:166 and SEQ ID NO:280; xiii) SEQ ID NO:167 and SEQ ID NO:281; xiv) SEQ ID NO:168 and SEQ ID NO:282; xv) SEQ ID NO:372 and SEQ ID NO:373; xvi) SEQ ID NO:376 and SEQ ID NO:377; xvii) SEQ ID NO:380 and SEQ ID NO:381; and xviii) SEQ ID NO:384 and SEQ ID NO:385.

107. The composition of any one of claims 104 to 106, wherein said VH encoding polynucleotide and said VL encoding polynucleotide comprise, respectively, nucleotide sequences selected from the group consisting of: (a) SEQ ID NO:173 and SEQ ID NO:185; (b) SEQ ID NO:174 and SEQ ID NO:186; (c) SEQ ID NO:175 and SEQ ID NO:187; (d) SEQ ID NO:176 and SEQ ID NO:188; (e) SEQ ID NO:178 and SEQ ID NO:189; (f) SEQ ID NO: 179 and SEQ ID NO:190; (g) SEQ ID NO:180 and SEQ ID NO:191; (h) SEQ ID NO:181 and SEQ ID NO:192; (i) SEQ ID NO:182 and SEQ ID NO:193; (j) SEQ ID NO:183 and SEQ ID NO:194; (k) SEQ ID NO:370 and SEQ ID NO:371; (1) SEQ ID NO:374 and SEQ ID NO:375; (m) SEQ ID NO:378 and SEQ ID NO:379; and (n) SEQ ID NO:382 and SEQ ID NO:383.

108. The composition of any one of claims 104 to 107, wherein said VH encoding polynucleotide and said VL encoding polynucleotide are contained in the same open reading - 142 frame, such that the VH and VL polypeptide encoded by said polynucleotides are comprised in a single-chain antibody or fragment thereof.

109. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL specifically binds to a linear epitope.

110. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL specifically binds to a non-linear conformational epitope.

111. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL specifically binds to the Sp35 LRR domain.

112. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL specifically binds to the Sp35 LRRNT domain.

113. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL specifically binds to the Sp35 LRRCT domain.

114. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL specifically binds to the Sp35 immunoglobulin domain.

115. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL specifically binds to the Sp35 basic region.

116. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is a multivalent antibody molecule comprising at least two heavy chains and at least two light chains.

117. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is multispecific.

118. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is bispecific.

119. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is monovalent, bivalent, polyvalent, or bifunctional.

120. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is humanized.

121. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is chimeric.

122. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is primatized.

123. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is fully human. - 143 124. . The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is an Fab fragment.

125. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is an Fab' fragment.

126. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is an F(ab) 2 fragment.

127. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VII and VL is an Fv fragment.

128. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is a single chain antibody.

129. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL specifically binds to a Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide with an affinity characterized by a dissociation constant (KD) no greater than 5 x 102 M, 102 M, 5 x 10-3 M, 104 M, 5 x 10~4 M, 1 0 4 M, 5 x 10-' M, 10- M, 5 x 10- M, 10 6 M, 5 x 10~7 M, 10-7 M, 5 x 10- M, 108 M, 5 x 10-9 M, 10-9 M, 5 x 101o M, 10-1 M, 5 x 10~" M, 10~" M, 5 x 10-12 M, 10-12 M, 5 x 10-1 3 M, 10-13 M, 5 x 10~" M, 10-14 M, 5 x 10~" M, or 10-1 M.

130. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL preferentially binds to a human Sp35 polypeptide or fragment thereof, relative to a murine Sp35 polypeptide or fragment thereof.

131. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is an antagonist of Sp35 mediated neurite outgrowth inhibition.

132. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is an antagonist of Sp35-mediated myelination inhibition.

133. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is an antagonist of Sp35 mediated oligodendrocyte cell death.

134. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is an antagonist of Sp35 mediated oligodendrocyte differentiation inhibition.

135. The composition of any one of claims 104 to 107, wherein an antibody or antigen-binding fragment thereof comprising said VH and VL is an antagonist of Sp35 mediated oligodendrocyte proliferation inhibition.

136. A vector comprising the polynucleotide of any one of claims 42 to 102. -144

137. The vector of claim 136, wherein said polynucleotide is operably associated with a promoter.

138. The vector of claim 136, wherein said polynucleotide encoding a VH and said polynucleotide encoding a VL are fused in frame, are co-transcribed from a single promoter operably associated therewith, and are cotranslated into a single chain antibody or antigen-binding fragment thereof.

139. The vector of claim 136, wherein said polynucleotide encoding a VH and said polynucleotide encoding a VL are co-transcribed from a single promoter operably associated therewith, but are separately translated.

140. The vector of claim 139, further comprising an IRES sequence disposed between said polynucleotide encoding a VH and said polynucleotide encoding a VL.

141. The vector of claim 139, wherein said polynucleotide encoding a VH and said polynucleotide encoding a VL are separately transcribed, each being operably associated with a separate promoter.

142. The vector of claim 141, wherein said separate promoters are copies of the same promoter.

143. The vector of claim 141, wherein said separate promoters non-identical.

144. A composition comprising the vector of any one of claims 136 to 143.

145. A composition comprising a first vector comprising a VH encoding polynucleotide of any one of claims 45 to 57 or 74 to 102, and a second vector comprising a VL encoding polynucleotide of any one of claims 58 to 73 or 74 to 102.

146. A host cell comprising the polynucleotide of any one of claims 42 to 102 or the vector of any one of claims 136 to 145.

147. A host cell comprising at least a first and a second vector, wherein said first and said second vectors are non-identical, wherein said first vector comprises the polynucleotide of any one of claims 42 to 57 or 74 to 112 which encodes an immunoglobulin heavy chain variable region, and wherein said second vector comprises the polynucleotide of any one of claims 58 to 73 or 74 to 102 which encodes an immunoglobulin light chain variable region.

148. A method of producing an anti-Sp35 antibody, comprising culturing the host cell of any one of claims 146 to 147, and recovering said antibody.

149. An anti-Sp35 antibody, or antigen-binding fragment thereof, produced by the method of claim 148.

150. An isolated polypeptide comprising an immunoglobulin heavy chain variable region (VH), wherein the CDR1, CDR2, and CDR3 regions of said VH are at least 90% identical, respectively, to reference heavy chain CDRI, CDR2, and CDR3 sequences selected from the group consisting of: a) SEQ ID NO:6, SEQ D NO:8, and SEQ ID NO:10, - 145 b) SEQ ID NO:12, SEQ ID NO:14, and SEQ ID NO:16, c) SEQ ID NO:18, SEQ ID NO:20, and SEQ ID NO:22, d) SEQ ID NO:24, SEQ ID NO:26, and SEQ ID NO:28, e) SEQ ID NO:30, SEQ ID NO:32, and SEQ ID NO:34, f) SEQ ID NO:36, SEQ ID NO:38, and SEQ ID NO:40, g) SEQ ID NO:42, SEQ ID NO:44, and SEQ ID -NO:46, h) SEQ ID NO:48, SEQ ID NO:50, and SEQ ID NO:52, i) SEQ ID NO:54, SEQ ID NO:56, and SEQ ID NO:58, j) SEQ ID NO:60, SEQ ID NO:61, and SEQ ID NO:62, k) SEQ ID NO:64, SEQ ID NO:66, and SEQ ID NO:68, 1) SEQ ID NO:66, SEQ ID NO:68, and SEQ ID NO:70, n) SEQ ID NO:72, SEQ ID NO:74, and SEQ ID NO:76, n) SEQ ID NO:77, SEQ ID NO:78, and SEQ ID NO:79, o) SEQ ID NO:80, SEQ ID NO:81, and SEQ ID NO:82, p) SEQ ID NO:83, SEQ ID NO:84, and SEQ ID NO:85; q) SEQ ID NO:195 SEQ ID NO:196 and SEQ ID NO:197; r) SEQ ID NO:198 SEQ ID NO:199 and SEQ ID NO:200; s) SEQ ID NO:201 SEQ ID NO:202 and SEQ ID NO:203; t) SEQ ID NO:204 SEQ ID NO:205 and SEQ ID NO:206; u) SEQ ID NO:207 SEQ ID NO:208 and SEQ ID NO:209; v) SEQ ID NO:210 SEQ ID NO:211 and SEQ ID NO:212; w) SEQ ID NO:213 SEQ ID NO:214 and SEQ ID NO:215; x) SEQ ID NO:216 SEQ ID NO:217 and SEQ ID NO:218; y) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; z) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; aa) SEQ ID NO:222 SEQ ID NO:223 and SEQ ID NO:224; bb) SEQ ID NO:225 SEQ ID NO:226 and SEQ ID NO:227; cc) SEQ ID NO:228 SEQ ID NO:229 and SEQ ID NO:230; dd) SEQ ID NO:231 SEQ ID NO:232 and SEQ ID NO:233; ee) SEQ ID NO:389 SEQ ID NO:390 and SEQ ID NO:391; ff) SEQ ID NO:395 SEQ ID NO:396 and SEQ ID NO:397; gg) SEQ ID NO:401 SEQ ID NO:402 and SEQ ID NO:403; and hh) SEQ ID NO:407 SEQ ID NO:408 and SEQ ID NO:409. and wherein an antibody or antigen-binding fragment thereof comprising said VH specifically binds to Sp35. - 146

151. An isolated polypeptide comprising an immunoglobulin heavy chain variable region (VH), wherein the CDR1, CDR2, and CDR3 regions of said VH are identical respectively, except for less than 20 conservative amino acid substitutions, to reference heavy chain CDR1, CDR2, and CDR3 sequences selected from the group consisting of: a) SEQ D NO:6, SEQ ID NO:8, and SEQ ID NO:10, b) SEQ ID NO:12, SEQ ID NO:14, and SEQ ID NO:16, c) SEQ ID NO:18, SEQ ID NO:20, and SEQ ID NO:22, d) SEQ ID NO:24, SEQ ID NO:26, and SEQ ID NO:28, e) SEQ ID NO:30, SEQ ID NO:32, and SEQ ID NO:34, f) SEQ ID NO:36, SEQ ID NO:38, and SEQ ID NO:40, g) SEQ ID NO:42, SEQ ID NO:44, and SEQ ID NO:46, h) SEQ ID NO:48, SEQ ID NO:50, and SEQ ID NO:52, i) SEQ ID NO:54, SEQ ID NO:56, and SEQ ID NO:58, j) SEQ ID NO:60, SEQ ID NO:61, and SEQ ID NO:62, k) SEQ ID NO:64, SEQ ID NO:66, and SEQ ID NO:68, 1) SEQ ID NO:66, SEQ ID NO:68, and SEQ ID NO:70, m) SEQ ID NO:72, SEQ ID NO:74, and SEQ ID NO:76, n) SEQ ID NO:77, SEQ ID NO:78, and SEQ ID NO:79, o) SEQ ID NO:80, SEQ ID NO:81, and SEQ ID NO:82, p) SEQ ID NO:83, SEQ ID NO:84, and SEQ ID NO:85; q) SEQ ID NO:195 SEQ ID NO:196 and SEQ ID NO: 197 ; r) SEQ ID NO:198 SEQ ID NO:199 and SEQ ID NO:2 00 ; s) SEQ ID NO:201 SEQ ID NO:202 and SEQ ID NO:203; t) SEQ ID NO:204 SEQ ID NO:205 and SEQ ID NO:206; u) SEQ ID NO:207 SEQ ID NO:208 and SEQ ID NO:209; v) SEQ ID NO:210 SEQ ID NO:211 and SEQ ID NO:212; w) SEQ ID NO:213 SEQ ID NO:214 and SEQ ID NO:215; x) SEQ ID NO:216 SEQ ID NO:217 and SEQ ID NO:218; y) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; z) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; aa) SEQ ID NO:222 SEQ ID NO:223 and SEQ ID NO:224; bb) SEQ ID NO:225 SEQ ID NO:226 and SEQ ID NO:227; cc) SEQ ID NO:228 SEQ ID NO:229 and SEQ ID NO:230; dd) SEQ ID NO:231 SEQ ID NO:232 and SEQ ID NO:233; ee) SEQ ID NO:389 SEQ ID NO:390 and SEQ ID NO:391; ff) SEQ ID NO:395 SEQ ID NO:396 and SEQ ID NO:397; -147 gg) SEQ ID NO:401 SEQ ID NO:402 and SEQ ID NO:403; and hh) SEQ ID NO:407 SEQ ID NO:408 and SEQ ID NO:409. and wherein an antibody or antigen-binding fragment thereof comprising said VH specifically binds to Sp35.

152. An isolated polypeptide, comprising an immunoglobulin heavy chain variable region (VH), wherein the CDR1, CDR2, and CDR3 regions of said VH are selected from the group consisting of: a) SEQ ID NO:6, SEQ ID NO:8, and SEQ ID NO:10, b) SEQ ID NO:12, SEQ ID NO:14, and SEQ ID NO:16, c) SEQ ID NO: 18, SEQ ID NO:20, and SEQ ID NO:22, d) SEQ ID NO:24, SEQ ID NO:26, and SEQ ID NO:28, e) SEQ ID NO:30, SEQ ID NO:32, and SEQ ID NO:34, f) SEQ ID NO:36, SEQ ID NO:38, and SEQ ID NO:40, g) SEQ ID NO:42, SEQ ID NO:44, and SEQ ID NO:46, h) SEQ ID NO:48, SEQ ID NO:50, and SEQ ID NO:52, i) SEQ ID NO:54, SEQ ID NO:56, and SEQ ID NO:58, j) SEQ ID NO:60, SEQ ID NO:61, and SEQ ID NO:62, k) SEQ ID NO:64, SEQ ID NO:66, and SEQ ID NO:68, 1) SEQ ID NO:66, SEQ ID NO:68, and SEQ ID NO:70, m) SEQ ID NO:72, SEQ ID NO:74, and SEQ ID NO:76, n) SEQ ID NO:77, SEQ ID NO:78, and SEQ ID NO:79, o) SEQ ID NO:80, SEQ ID NO:81, and SEQ ED NO:82, p) SEQ ID NO:83,.SEQ ID NO:84, and SEQ ID NO:85; q) SEQ ID NO:195 SEQ ID NO:196 and SEQ ID NO:197; r) SEQ ID NO:198 SEQ ID NO:199 and SEQ ID NO:200; s) SEQ ID NO:201 SEQ ID NO:202 and SEQ ID NO:203; t) SEQ ID NO:204 SEQ ID NO:205 and SEQ ID NO:206; u) SEQ ID NO:207 SEQ ID NO:208 and SEQ ID NO:209; v) SEQ ID NO:210 SEQ ID NO:211 and SEQ ID NO:212; w) SEQ ID NO:213 SEQ ID NO:214 and SEQ ID NO:215; x) SEQ ID NO:216 SEQ ID NO:217 and SEQ ID NO:218; y) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; z) SEQ ID NO:219 SEQ ID NO:220 and SEQ ID NO:221; aa) SEQ ID NO:222 SEQ ID NO:223 and SEQ ID NO:224; bb) SEQ D NO:225 SEQ ID NO:226 and SEQ ID NO:227; cc) SEQ D NO:228 SEQ ID NO:229 and SEQ ID NO:230; - 148 dd) SEQ ID NO:231 SEQ ID NO:232 and SEQ ID NO:233 ee) SEQ ID NO:389 SEQ ID NO:390 and SEQ ID NO:391; ff) SEQ ID NO:395 SEQ ID NO:396 and SEQ ID NO:397; gg) SEQ ID NO:401 SEQ ID NO:402 and SEQ ID NO:403; and hh) SEQ ID NO:407 SEQ ID NO:408 and SEQ ID NO:409.

153. An isolated polypeptide comprising a VH at least 90% identical to a reference VH sequence selected from the group consisting of SEQ ID NOs: 158 to 172, 372, 376, 380 and 384 wherein an antibody or antigen-binding fragment thereof comprising said VH specifically binds to Sp 3 5 .

154. An isolated polypeptide comprising a VH identical to a reference VH sequence selected from the group consisting of SEQ ID NOs: 158 to 172, 372, 376, 380 and 384, except for less than 20 conservative amino acid substitutions, and wherein an antibody or antigen-binding fragment thereof comprising said VH specifically binds to Sp35.

155. The polypeptide of claim 153, wherein said VH is selected from the group consisting of SEQ ID NOs: 158 to 172, 373, 377, 381 and 385.

156. The polypeptide of any one of claims 150 to 155, wherein an antibody or antigen-binding fragment thereof comprising said VH specifically binds to the same epitope as a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3PlD1O.2C3, 3PlEl1.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (LiO2), 35-E04 (Li03), 36-C09 (Li04), 30-Al1 (Li05), 34-F02 (Li06), 29-E07 (Li07), 34-G04 (LiO8), 36-A12 (Li09), 28-D02 (LilO), 30-BOl (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (L1a.10), 3571 (Lla.1 1), 3582 (Lla.12), and 1968 (Lla.13).

157. The polypeptide of any one of claims 150 to 155, wherein an antibody or antigen-binding fragment thereof comprising said VH competitively inhibits a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3P1D10.2C3, 3PIE11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO 1 (LiO2), 35-E04 (Li03), 36-C09 (LiO4), 30-Al1 (Li05), 34-F02 (Li06), 29 E07 (Li07), 34-G04 (LiO8), 36-A12 (Li09), 28-D02 (LilO), 30-BOl (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lia.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13) from binding to Sp35.

158. The polypeptide of any one of claims 150 to 157, wherein an antibody or antigen-binding fragment thereof comprising said VH specifically binds to a Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no - 149 greater than 5 x 10-2 M, 102 M, 5 x 10- M, 104 M, 5 x 1 0 ~4 M, 10~4 M, 5 x 10~' M, 10-' M, 5 x 106 M, 10~6 M, 5 x 10-7 M, 10- M, 5 x 10~8 M, 10- M, 5 x 10- M, 104 M, 5 x 1010 M, 10 M, 5 x 10~ " M, 10-" M, 5 x 1012 M, 10~" M, 5 x 10-" M, 10-3 M, 5 x 10-4 M, 10-4 M, 5 x 10s M, or 10-" M.

159. An isolated polypeptide comprising an immunoglobulin light chain variable region (VL), wherein the CDR1, CDR2, and CDR3 regions of said VL are at least 90% identical, respectively, to reference light chain CDR1, CDR2, and CDR3 sequences selected from the group consisting of: a) SEQ ID NO:87, SEQ ID NO:89, and SEQ ID NO:91; b) SEQ ID NO:93, SEQ ID NO:95, and SEQ ID NO:97; c) SEQ ID NO:99, SEQ ID NO:101, and SEQ ID NO:103; d) SEQ IDNO:105, SEQ ID NO:107, and SEQ ID NO:109; e). SEQ ID NO:111, SEQ ID NO:113, and SEQ ID NO:115; f) SEQ ID NO:117, SEQ ID NO:119, and SEQ ID NO:12 1 ; g) SEQ ID NO:123, SEQ ID NO:125, and SEQ ID NO:127; h) SEQ ID NO:129, SEQ ID NO:131, and SEQ ID NO:13 3 ; i) SEQ ID NO:135, SEQ ID NO:137, and SEQ ID NO:139; j) SEQ ID NO:141, SEQ ID NO:143, and SEQ ID NO: 14 5 ; k) SEQ ID NO:146, SEQ ID NO:147, and SEQ ID NO:148; 1) SEQ ID NO:149, SEQ ID NO:150, and SEQ ID NO:151; m) SEQ IDNO:152, SEQIDNO:153, and SEQ DNO:154; n) SEQ ID NO:155, SEQ ID NO:156, and SEQ ID NO:157; o) SEQ ID NO:234, SEQ ID NO:235, and SEQ ID NO:236, p) SEQ ID NO:237, SEQ ID NO:238, and SEQ ID NO:239; q) SEQ ID NO:240, SEQ ID NO:241, and SEQ ID NO:242; r) SEQ ID NO:243, SEQ ID NO:244, and SEQ ID NO:245; s) SEQ ID NO:246, SEQ ID NO:247, and SEQ ID NO:248; t) SEQ ID NO:249, SEQ ID NO:250, and SEQ ID NO:251; u) SEQ ID NO:252, SEQ ID NO:253, and SEQ ID NO:254; v) SEQ ID NO:255, SEQ ID NO:256, and SEQ ID NO:257; w) SEQ ID NO:258, SEQ ID NO:259, and SEQ ID NO:260; x) SEQ ID NO:261, SEQ ID NO:262, and SEQ ID NO:263; y) SEQ ID NO:264, SEQ D NO:265, and SEQ ID NO:266; z) SEQ ID NO:267, SEQ ID NO:268, and SEQ ID NO:269; aa) SEQ ID NO:270, SEQ ID NO:271, and SEQ ID NO:272; bb) SEQ ID NO:386, SEQ ID NO:387, and SEQ ID NO:388; cc) SEQ ID NO:392, SEQ ID NO:393, and SEQ ID NO:394; -150 dd) SEQ ID NO:398, SEQ ID NO:399, and SEQ ID NO:400; and ee) SEQ ID NO:404, SEQ ID NO:405, and SEQ ID NO:406. and wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to Sp35.

160. An isolated polypeptide comprising an immunoglobulin light chain variable region (VL), wherein the CDRI, CDR2, and CDR3 regions of said VL are identical, respectively, except for less than 20 conservative amino acid substitutions, to reference light chain CDR1, CDR2, and CDR3 sequences selected from the group consisting of: a) SEQ ID NO:87, SEQ ID NO:89, and SEQ ID NO:91; b) SEQ ID NO:93, SEQ ID NO:95, and SEQ ID NO:97; c) SEQ ID NO:99, SEQ ID NO:101, and SEQ ID NO:103; d) SEQ ID NO:105, SEQ ID NO:107, and SEQ ID NO:10 9 ; e) SEQ ID NO:11, SEQ ID NO:113, and SEQ ID NO:115; f) SEQ ID NO:117, SEQ ID NO:119, and SEQ ID NO:121; g) SEQ ID NO:123, SEQ ID NO:125, and SEQ ID NO:1 27 ; h) SEQ ID NO:129, SEQ ID NO:131, and SEQ ID NO:133; i) SEQ ID NO:135, SEQ ID NO:137, and SEQ ID NO:139; j) SEQ ID NO:141, SEQ ID NO:143, and SEQ ID NO:145; k) SEQ ID NO:146, SEQ ID NO:147, and SEQ ID NO: 148; 1) SEQ ID NO:149, SEQ ID NO:150, and SEQ ID NO:151; m) SEQ IDNO:152, SEQ IDNO:153, and SEQ ID NO:154; n) SEQ ID NO:155, SEQ ID NO:156, and SEQ ID NO:157; o) SEQ ID NO:234, SEQ ID NO:235, and SEQ ID NO:236, p) SEQ ID NO:237, SEQ ID NO:238, and SEQ ID NO:239; q) SEQ ID NO:240, SEQ ID NO:241, and SEQ ID NO:242; r) SEQ ID NO:243, SEQ ID NO:244, and SEQ ID NO:245; s) SEQ ID NO:246, SEQ ID NO:247, and SEQ ID NO:248; t) SEQ ID NO:249, SEQ ID NO:250, and SEQ ID NO:25 1; u) SEQ ID NO:252, SEQ ID NO:253, and SEQ ID NO:254; v) SEQ ID NO:255, SEQ ID NO:256, and SEQ ID NO:257; w) SEQ ID NO:258, SEQ ID NO:259, and SEQ ID NO:260; x) SEQ ID NO:261, SEQ ID NO:262, and SEQ ID NO:263; y) SEQ ID NO:264, SEQ ID NO:265, and SEQ ID NO:266; z) SEQ ID NO:267, SEQ ID NO:268, and SEQ ID NO:269; aa) SEQ ID NO:270, SEQ ID NO:271, and SEQ ID NO:272; -151 bb) SEQ ID NO:386, SEQ ID NO:387, and SEQ ID NO:388; cc) SEQ ID NO:392, SEQ ID NO:393, and SEQ ID NO:394; dd) SEQ ID NO:398, SEQ ID NO:399, and SEQ ID NO:400; and ee) SEQ ID NO:404, SEQ ID NO:405, and SEQ ID NO:406. and wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to Sp35.

161. An isolated polypeptide comprising an immunoglobulin light chain variable region (VL), wherein the CDR1, CDR2, and CDR3 regions of said VL are selected from the group consisting of: a) SEQ ID NO:87, SEQ ID NO:89, and SEQ ID NO:91; b) SEQ ID NO:93, SEQ ID NO:95, and SEQ ID NO:97; c) SEQ ID NO:99, SEQ ID NO:101, and SEQ ID NO:103; d) SEQ ID NO:105, SEQ ID NO:107, and SEQ ID NO:109; e) SEQ ID NO:111, SEQ ID NO:113, and SEQ ID NO:115; f) SEQ ID NO:117, SEQ ID NO:119, and SEQ ID NO:12 1 ; g) SEQ ID NO:123, SEQ ID NO:125, and SEQ ID NO:127; h) SEQ ID NO:129, SEQ ID NO:131, and SEQ ID NO:133; i) SEQ ID NO:135, SEQ ID NO:137, and SEQ ID NO:139; j) SEQ ID NO:141, SEQ ID NO:143, and SEQ ID NO:145; k) SEQ ID NO:146, SEQ ID NO:147, and SEQ ID NO: 148; 1) SEQ ID NO:149, SEQ ID NO:150, and SEQ ID NO:151; m) SEQ ID NO:152, SEQ ID NO:153, and SEQ ID NO:154; n) SEQ ID NO:155, SEQ ID NO:156, and SEQ ID NO:157; o) SEQ ID NO:234, SEQ ID NO:235, and SEQ ID NO:236, p) SEQ ID NO:237, SEQ ID NO:238, and SEQ ID NO:239; q) SEQ ID NO:240, SEQ ID NO:241, and SEQ ID NO:242; r) SEQ ID NO:243, SEQ ID NO:244, and SEQ ID NO:245; s) SEQ ID NO:246, SEQ ID NO:247, and SEQ ID NO:248; t) SEQ ID NO:249, SEQ ID NO:250, and SEQ ID NO:251; u) SEQ ID NO:252, SEQ ID NO:253, and SEQ ID NO:254; v) SEQ ID NO:255, SEQ ID NO:256, and SEQ ID NO:257; w) SEQ ID NO:258, SEQ ID NO:259, and SEQ ID NO:260; x) SEQ ID NO:261, SEQ ID NO:262, and SEQ ID NO:263; y) SEQ ID NO:264, SEQ ID NO:265, and SEQ ID NO:266; z) SEQ ID NO:267, SEQ ID NO:268, and SEQ ID NO:269; aa) SEQ ID NO:270, SEQ ID NO:271, and SEQ ID NO:272 -152 bb) SEQ ID NO:386, SEQ ID NO:387, and SEQ ID NO:388; cc) SEQ ID NO:392, SEQ ID NO:393, and SEQ ID NO:394; dd) SEQ ID NO:398, SEQ ID NO:399, and SEQ ID NO:400; and ee) SEQ ID NO:404, SEQ ID NO:405, and SEQ ID NO:406.

162. An isolated polypeptide comprising a VL at least 90% identical to a reference VL sequence selected from the group consisting of SEQ ID NOs: 273 to 286, 373, 377, 381 and 385, wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to Sp 35 .

163. An isolated polypeptide comprising a VL identical to a reference VL sequence, except for less than 20 conservative amino acid substitutions, selected from the group consisting of SEQ ID NOs:273 to 286, 373, 377, 381 and 385, wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to Sp35.

164. The polypeptide of any one of claims 162 or 163, wherein said VL is selected from the group consisting of SEQ ID NOs:273 to 286, 373, 377, 381 and 385.

165. The polypeptide of any one of claims 159 to 164, wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to the same epitope as a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3PlD1O.2C3, 3P1E11.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DO1 (Li02), 35-E04 (Li03), 36-C09 (LiO4), 30-Al1 (Li05), 34-F02 (LiO6), 29-E07 (Li07), 34-G04 (Li08), 36-A12 (Li09), 28-D02 (LilO), 30-BOl (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (Lla.13).

166. The polypeptide of any one of claims 159 to 164, wherein an antibody or antigen-binding fragment thereof comprising said VL competitively inhibits a monoclonal antibody selected from the group consisting of 201', 3A3, 3A6, 1A7, 1G7, 2B10, 2C11, 2F3, 3P1D10.2C3, 3P1EI1.3B7, 3P2C6.3G10.2H7, 3P2C9.2G4, 3P4A6.1D9, 3P4A1.2B9, 3P4C2.2D2, 3P4C5.1D8, 3P4C8.2G9, 30-C12 (LiOl), 38-DOI (Li02), 35-E04 (Li03), 36-C09 (LiO4), 30-All (LiO5), 34-F02 (LiO6), 29 E07 (Li07), 34-G04 (Li08), 36-A12 (Li09), 28-D02 (LilO), 30-BO (Lill), 34-B03 (Lil2), Lil3, Li32, Li33, Li34, 3383 (Lla.1), 3495(Lla.2), 3563 (Lla.3), 3564 (Lla.4), 3565 (Lla.5), 3566 (Lla.6), 3567 (Lla.7), 3568 (Lla.8), 3569 (Lla.9), 3570 (Lla.10), 3571 (Lla.11), 3582 (Lla.12), and 1968 (LI a.13) from binding to Sp35.

167. The polypeptide of any one of claims 159 to 166, wherein an antibody or antigen-binding fragment thereof comprising said VL specifically binds to a Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide, with an affinity characterized by a dissociation constant (KD) no greater than 5 x 102 M, 10.2 M, 5 x 104 M, 10- M, 5 x 1 0 4 M, 1 0 4 M, 5 x 10- M, 10~ M, 5 x 10- -153 M, 10-6 M, 5 x 104 M, 10- M, 5 x 10-8 M, 10- M, 5 x 109 M, 109 M, 5 x 1010 M, 10' 0 M, 5 x 10~ " M, 10~" M, 5 x 10-12 M, 10~12 M, 5 x 10~" M, 10-' M, 5 x 104 M, 10-14 M, 5 x 10~" M, or 10~ M.

168. The polypeptide of any one of claims 150 to 167, further comprising a heterologous polypeptide fused thereto.

169. The polypeptide of any one of claims 150 to 168, wherein said polypeptide is conjugated to an agent selected from the group consisting of a therapeutic agent, a prodrug, a peptide, a protein, an enzyme, s virus, a lipid, a biological response modifier, a pharmaceutical agent, or PEG.

170. A composition comprising the polypeptide of any one of claims 150 to 169, wherein an antibody or antigen-binding fragment thereof comprising said VH and said VL specifically binds to Sp35.

171. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL specifically binds to a linear epitope.

172. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL specifically binds to a non-linear conformational epitope.

173. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL specifically binds to the Sp35 LRR domain.

174. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL specifically binds to the Sp3 5 LRRNT domain.

175. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VI, said VL, or both said VH and VL specifically binds to the Sp3 5 LRRCT domain.

176. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VI, said VL, or both said VH and VL specifically binds to the Sp35 Basic region.

177. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL specifically binds to the Sp3 5 iminunoglobulin domain.

178. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both -154 said VH and VL is a multivalent antibody molecule comprising at least two heavy chains and at least two light chains.

179. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is multispecific.

180. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is bispecific.

181. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is monovalent, bivalent, polyvalent, or bifunctional.

182. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is humanized.

183. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is chimeric.

184. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is primatized.

185. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is fully human.

186. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is an Fab fragment.

187. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is an Fab' fragment.

188. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is an F(ab) 2 fragment.

189. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is an Fv fragment. -155

190. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is a single chain antibody.

191. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL specifically binds to a Sp35 polypeptide or fragment thereof, or a Sp35 variant polypeptide with an affinity characterized by a dissociation constant (KD) no greater than 5 x 10-2 M, 102 M, 5 x 10 M, 10 M, 5 x 10~4 M, 10-4 M, 5 x 10-' M, 10~5 M, 5 x 10^' M, 10-' M, 5 x 10-1 M, 10 7 M, 5 x 10- M, 10-' M, 5 x 10- M, 10- M, 5 x 10-1 M, 10-10 M, 5 x 10-" M, 10-" M, 5 x 10-12 M, 10^12 M, 5 x 101 M, 10-' M, 5 x 1014 M, 10-4 M, 5 x 10-1 M, or 10-"1 M..

192. The polypeptide of any one of claims 150 to 169 or the composition of claim 170, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL preferentially binds to a human Sp35 polypeptide or fragment thereof, relative to a murine. Sp3 5 polypeptide or fragment thereof.

193. A composition comprising the polypeptide of any one of claims 150 to 192, and a carrier.

194. The polypeptide of any one of claims 150 to 192 or the composition of any one of claims 170 or 193, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is an antagonist of Sp35 mediated neurite outgrowth inhibition.

195. The polypeptide of any one of claims 150 to 192 or the composition of any one of claims 170 or 193, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is an antagonist of Sp35-mediated myelination inhibition.

196. The polypeptide of any one of claims 150 to 192 or the composition of any one of claims 170 or 193, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is an antagonist of Sp35 mediated oligodendrocyte cell death.

197. The polypeptide of any one of claims 150 to 192 or the composition of any one of claims 170 or 193, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is an antagonist of Sp35 mediated oligodendrocyte differentiation inhibition.

198. The polypeptide of any one of claims 150 to 192 or the composition of any one of claims 170 or 193, wherein an antibody or antigen-binding fragment thereof comprising said VH, said VL, or both said VH and VL is an antagonist of Sp35 mediated oligodendrocyte proliferation inhibition.

199. An isolated antibody or antigen binding fragment thereof comprising the polypeptide of any one of claims 150 to 169.

200. A method for treating CNS injury comprising administering to an animal suffering from such injury an effective amount of an agent selected from the group consisting of the isolated Sp35 -156 antibody or fragment thereof of any one of claims 1 to 41 or 199, the isolated polynucleotide of any one of claims 42 to 102, the isolated polypeptide of any one of claims 150 to 192 or 194 to 198, or the composition of any one of claims 103 to 135, 144 or 193.

201. The method of claim 200, wherein said CNS injury is selected from the group consisting of traumatic brain injury, spinal cord injury, and optic nerve injury.

202. A method for treating diseases or disorders associated with inhibition of neuronal growth in the CNS comprising administering to an animal in need of said treatment an effective amount of an agent selected from the group consisting of the isolated Sp35 antibody or fragment thereof of any one of claims 1 to 41 or 199, the isolated polynucleotide of any one of claims 42 to 102, the isolated polypeptide of any one of claims 150 to 192 or 194 to 198, or the composition of any one of claims 103 to 135, 144 or 193.

203. The method of claim 202, wherein said disease or disorder is selected from the group consisting of ALS, Huntington's disease, Alzheimer's disease, Parkinson's disease, diabetic neuropathy, and stroke.

204. A method for treating diseases or disorders associated with inhibition of oligodendrocyte growth or differentiation comprising administering to an animal in need of said treatment an effective amount of an agent selected from the group consisting of the isolated Sp35 antibody or fragment thereof of any one of claims 1 to 41 or 199, the isolated polynucleotide of any one of claims 42 to 102, the isolated polypeptide of any one of claims 150 to 192 or 194 to 198, or the composition of any one of claims 103 to 135, 144 or 193.

205. A method for treating diseases or disorders associated with demyelination or dysmyelination of CNS neurons comprising administering to an animal in need of said treatment an effective amount of an agent selected from the group consisting of the isolated Sp35 antibody or fragment thereof of any one of claims 1 to 41 or 199, the isolated polynucleotide of any one of claims 42 to 102, the isolated polypeptide of any one of claims 150 to 192 or 194 to 198, or the composition of any one of claims 103 to 135, 144 or 193.

206. The method of claim 205, wherein said disease or disorder is selected from the group consisting of multiple sclerosis (MS), progressive multifocal leukoencephalopathy (PML), encephalomyelitis (EPL), central pontine myelolysis (CPM), Wallerian Degeneration, adrenoleukodystrophy, Alexander's disease, and Pelizaeus Merzbacher disease (PMZ).

207. The method of claim 206, wherein said disease or disorder is multiple sclerosis.

208. The method of any one of claims 200 to 207, wherein said animal is a mammal.

209. The method of claim 208, wherein said mammal is a human

210. A method of inhibiting signal transduction by NgRI, comprising contacting the NgRI with an effective amount of an an agent selected from the group consisting of the isolated Sp35 antibody or fragment thereof of any one of claims 1 to 41 or 199, the isolated polynucleotide of -157 any one of claims 42 to 102, the isolated polypeptide of any one of claims 150 to 192 or 194 to 198, or the composition of any one of claims 103 to 135, 144 or 193.

211. A method of decreasing inhibition of axonal growth of a central nervous system (CNS) neuron, comprising contacting the neuron with an effective amount of an agent selected from the group consisting of the isolated Sp35 antibody or fragment thereof of any one of claims 1 to 41 or 199, the isolated polynucleotide of any one of claims 42 to 102, the isolated polypeptide of any one of claims 150 to 192 or 194 to 198, or the composition of any one of claims 103 to 135, 144 or 193.

212. A method of inhibiting growth cone collapse of a CNS neuron, comprising contacting the neuron with an effective amount of an agent selected from the group consisting of the isolated Sp35 antibody or fragment thereof of any one of claims I to 42 or 199, the isolated polynucleotide of any one of claims 42 to 102, the isolated polypeptide of any one of claims 150 to 192 or 194 to 198, or the composition of any one of claims 103 to 135, 144 or 193. Date: 23 January 2013