HK1172690B - Copeptin-based kit - Google Patents

Description

copeptin-based kit

The divisional application is based on the original Chinese patent application with the application number of 200580021434.9, the application date of 2004, 8/19/2004 and the name of the invention of "method for diagnosing diseases by copeptin".

The present invention relates to the use of copeptin and/or precursors or fragments thereof and/or splice variants thereof, copeptin-containing fragments and/or combinations and/or derivatives thereof as humoral biomarkers for disorders associated with or caused by non-physiological changes in the release of vasopressin from the neuropituitary, such as heart disease, kidney disease, inflammatory diseases and sepsis as well as diseases/disorders of the central nervous system and neurodegenerative diseases and other diseases as described below.

All of the above biomolecules and fragments, variants and combinations thereof, which share the common feature of exhibiting copeptin immunoreactivity, are hereinafter referred to as "copeptin" in the present application. Thus, the term "copeptin" also includes, inter alia, for example VP-prohormone, if present in the form of the sample itself.

Copeptin of the present invention for use as a biomarker, in particular a humoral biomarker, useful for diagnosing conditions associated with or caused by non-physiological changes, in particular an increase, in the release of vasopressin by the neurohypophysis, such as chronic or congestive heart failure, cardiac arrest, cardiogenic shock, cardiac infarction, acute myocardial infarction, arterial hypertension, cardiac surgery, cirrhosis, pulmonary disorders, nephropathy in polycystic kidney disease, diabetes insipidus, various forms of hyponatremia, various forms of syndrome of inappropriate secretion of anti-diuretic hormone, bleeding, states of edema formation, inflammatory diseases, trauma, burns, complications of their infection and sepsis, severe sepsis and septic shock, as well as diseases/conditions of the Central Nervous System (CNS) and neurodegenerative diseases.

In the present application, if reference is made to the use as biomarker, it means that the biomarker is determined in an in vitro sample of biological fluid (i.e. ex vivo) such as blood, serum or plasma and cerebrospinal fluid (cerebrospinal fluid; CSF). It is obvious to any skilled person that only such physiologically present "copeptin" molecules will be determined, and in fact they may be present in such samples. Several different kinds of substantially equivalent immunoreactivity may be present in a sample of body fluid, for example they differ in length and/or their pattern of presence (presence) and/or type and/or their degree of post-translational modification such as glycosylation and/or phosphorylation. Given the inherent possibility that any given assay may recognize more than one type of molecule, an assay according to a preferred embodiment copeptin will be understood as an assay for copeptin immunoreactivity, with immunoreactivity measured particularly preferably with the assay described hereinafter.

As far as the use of the present invention also extends to formulations for use as biomarkers, or as detection components and reagents in connection with copeptin assays as active ingredients in pharmaceuticals, any suitable peptide or derivative of copeptin, including fusion products and modifications having e.g. reduced homology to the native copeptin, or having improved stability, may be used, without being limited to the native copeptin product.

The term copeptin in the present invention therefore also includes amino acid sequences showing, for example, only 75% homology, preferably at least 80% homology, more preferably at least 90% homology to copeptin.

The terms "diagnosis" or "diagnosed" are used in this specification as general terms and, if not otherwise defined, include not only diagnosis in the sense of identifying a particular disease, but also screening asymptomatic or high risk populations at risk for or suspected of having a certain disease, monitoring untreated or treated patients and monitoring course of treatment and prognosis/early prognosis and survival prognosis.

The invention further relates to raised antibodies against copeptin or partial peptides of copeptin, in particular antibodies for use in the above method, as well as kits and assays involving such components.

The vasodilatory state of shock is a life threatening condition. Peripheral blood pressure drops sharply and often fails to normalize after catecholamines are administered. The most common form of shock is septic shock, which is also the most severe form of sepsis. Furthermore, vasodilatory shock manifests itself after major cardiac surgery, hemorrhagic and cardiogenic shock or after drug or toxin intoxication [1, 2 ].

A series of peptides that are significantly effective via the autocrine/paracrine pathway are involved in the regulation of blood pressure. The following molecules are known to have vasodilatory function: such as adrenomedullin, calcitonin gene-related peptide (CGRP and) and Atrial Natriuretic Peptide (ANP). The following molecules exhibit vasoconstrictive effects: endothelin, angiotensin II, and vasopressin (also known as arginine-vasopressin, antidiuretic hormone (ADH)).

Vasopressin is a breakdown product of a large precursor molecule ("VP prohormone"; the polypeptide sequence is shown in FIG. 3; or as SEQ ID NO: 4) that is formed mainly in neurons of the hypothalamus [20 ]. After synthesis VP prohormone is glycosylated in the golgi apparatus, encapsulated in secretory vesicles and cleaved by prohormone convertase SP3 into the three peptides vasopressin, neurotensin and copeptin. These peptides are secreted by vesicles upon receiving specific stimuli (e.g. high osmotic pressure, hypovolemia or different hormones) after axonal migration to the nerve endings of the pituitary.

The most important physiological role of vasopressin is the retention of water in the body (antidiuresis). The effect of vasopressin in physiologically raising blood pressure is less pronounced in healthy individuals than in septic shock. Other physiological functions of vasopressin are the regulation of the pituitary adrenal axis (ACTH, cortisol) to stimulate gastrointestinal activity and the aggregation of platelets [ 1; the numbers in parentheses refer to the appended reference sequence ].

Vasopressin plays an important role in the pathogenesis of shock: the plasma concentration of vasopressin after stimulation was shown to increase to three orders of magnitude above normal within 15 minutes in the experimental shock model [4 ]. The concentration of vasopressin decreases sharply in the course of the duration of the shock syndrome following the rapid release of vasopressin stored in the pituitary, which is observed in septic shock patients [5-7 ]. This observation, which underlies the principle of alternative therapies for the treatment of septic shock with vasopressin, has been successfully tested [8-10 ]. These results indicate that endogenous reductions in vasopressin promote septic shock state [5 ].

Vasopressin has also been investigated as a marker for the prediction of the survival probability of patients with cardiac arrest [11] and thus for the treatment of such patients [12 ].

Pathophysiological overexpression of vasopressin or of VP prohormones has been shown in several types of cancers, such as prostate, testicular, ovarian, and pancreatic, pituitary adenomas and gangliomas, olfactory neuroblastoma, breast and colon tumors, nasopharyngeal, brain and neck cancers, pheochromocytoma, and tumors of gastrointestinal origin, squamous cell carcinoma, adenocarcinoma, and large cell carcinoma [13, 24, 25, 26 ]. Vasopressin produced or released in cancer is considered to be pathophysiologically formed, i.e. formed by abnormal physiological pathways (altered pathological tissue) which differ from the normal physiological vasopressin production.

In the above diseases vasopressin is released from the organ from which it is normally derived (the neuropituitary), although at a non-physiological level.

copeptin-also known as C-terminal glycoprotein-contains 39 amino acids, its sugar groups and has a molecular weight of about 2000Da [15-17 ]. Glycosylation at position 131 of the precursor VP-prohormone (cf. SEQ ID NO: 4). The biological function of copeptin is not clear.

Direct determination of vasopressin as a diagnostic marker of body fluids, such as serum or plasma, is not suitable per se for routine diagnostics. More than 90% of vasopressin binds to platelets and is therefore not available for this measurement [21 ]. Thus the free vasopressin found in plasma does not reflect the actual amount of vasopressin released into the blood stream. The binding of vasopressin to platelets leads to different results, which are variable depending on the amount of platelets contained in the measurement and depending on the centrifugation method [22] used to obtain the plasma. Other obstacles are: the amount of vasopressin observed is higher if the blood sample is left at room temperature before centrifugation. These effects and the short half-life of vasopressin in vivo (24 min, [14]) and in ex vivo plasma samples even stored under-20 [23] have prevented the use of vasopressin in routine diagnostics. Due to the short half-life, sampling, obtaining plasma, transporting the sample to the laboratory and performing the diagnosis in the laboratory including the required tests before the critical level of detection of vasopressin is reached is not possible in routine diagnostics.

Due to the low stability of vasopressin in vivo and the variable results due to binding to and release from platelets, the use as biomarker even with an optimal sample delivery system is very limited, since the effects of degradation occur too quickly.

The object of the present invention is to overcome the adverse half-life of vasopressin and the variable effect of the results in the measurement and to study methods, applications and kits for the detection and determination of molecules associated with the release of vasopressin, more particularly copeptin, for the diagnosis of cardiovascular diseases and sepsis.

This object can be achieved based on the following surprising findings: certain fragments of VP prohormone-the precursor of vasopressin-especially copeptin, are useful as assay tools for the physiological release of vasopressin, especially in body fluids, in the diagnosis and monitoring of cardiovascular diseases and sepsis.

The production of fragments, in particular copeptin, is related to the release of vasopressin, since all fragments are derived from the same precursor.

Furthermore, it was found that the stability of these precursor proteins, fragments and/or combinations thereof in vitro is surprisingly high, making fragments, in particular copeptin, completely suitable for conventional purposes.

The linkage between the fragments such as copeptin and other fragments of the precursor peptide makes them suitable as diagnostic tools for all diseases where vasopressin plays a role. Copeptin is therefore especially useful in medical diagnostics for diagnosing and monitoring various diseases, in particular cardiovascular diseases and systemic inflammation, in particular sepsis.

Furthermore, in one embodiment the invention relates to the use of copeptin for the diagnosis of these diseases, for the control and prognosis of the course of the above mentioned diseases in which vasopressin plays a role.

Additional clinical data may support the identification of diseases.

It is also possible to use amino acid sequences which show at least 75% homology, preferably at least 80% homology, more preferably at least 90% homology with copeptin of the present invention.

Two regions of the amino acid sequence of the human vasopressin-neurotensin 2-copeptin-precursor (PATV 17; PLAY17) were selected as immunological binding sites for specific antibody recognition in a preferred embodiment of the invention according to the following examples:

132-147 bit: CATQLDGPAGALLLRLV (PATV17-SEQ ID NO: 1)

149-164 site: CLAGAPEPFEPAQPDAY (PLAY17-SEQ ID NO: 2).

For calibration purposes and for the preparation of standard solutions, a peptide containing the two binding sites described above (PAY33) was used:

132-164 position: ATQLDGPAGALLLRLVQLAGAPEPFEPAQPDAY (PAY33-SEQ ID NO: 3).

The immunological binding sites PATV17 and PLAY17 recognized by specific antibodies were chosen such that they did not contain a putative glycosylation site for copeptin at position 131. Thus, the presence or absence of a post-translational modification (glycosylation) of copeptin determined in assays using such antibodies will not have any significant effect on copeptin recognition. Thus, the term "copeptin" includes "naked" copeptin peptides and post-translationally modified forms of said peptides.

The above-mentioned peptides were synthesized as described below, the amino-terminal cysteine residue was added to each copeptin amino acid sequence, and the peptides of these soluble proteins were chemically synthesized according to a method known to those skilled in the art. They were purified and quality controlled by mass spectrometry and reverse phase HPLC and lyophilized into aliquots (Jerini AG, Berlin, Germany).

The synthetic peptides of the invention are used to produce antigens which are injected into animals to raise antibodies against copeptin of the invention. Different methods may be used to achieve these objectives as known to those skilled in the art.

In a preferred embodiment the peptides PATV17 and PLAY17 are linked to the carrier protein Keyhole Limpet Hemocyanin (KLH) via MBS (benzoyl-N-hydroxysuccinimide ester of m-maleic acid imide) according to the method of Pierce, Rockford, IL, USA. Antibodies against the above peptides were produced in sheep. In a preferred embodiment of the invention, polyclonal antibodies against the above peptides are raised. The antibody is purified according to known methods. In a preferred embodiment of the invention, this is preferably achieved by ligand-specific affinity chromatography by coupling the peptide via the amino-terminal cysteine residue to Pierce's sulfoLink-gel (Boston, USA) according to Pierce's method. In a preferred embodiment, the antibody is labeled with a detectable marker. The marker used is preferably a fluorescent marker, in a more preferred embodiment the antibody is labeled with a chemiluminescent marker, in a further preferred embodiment antibodies against PATV17(0413-pAK) and PLAY17(0417-pAK) are labeled with a chemiluminescent marker.

In other preferred embodiments the invention relates to the use of the antibodies produced for the detection of copeptin of the invention in a sample of bodily fluid, as well as to kits comprising an amount of such an antibody or antibodies specific for the detection of a molecule of the invention. These molecules can be detected using various assays known to those skilled in the art, including competition or sandwich immunoassays using multiple markers, either manually, automatically, or in the form of site of interest assays (point of care test formats).

Methods for detecting binding of antibodies to individual molecules are also known to those skilled in the art. All such known assay formats are usable within the scope of copeptin assays. For example by means of a rapid test device, for example of the immunochromatographic type, the so-called POC (site of interest) test, within the scope of the present invention. The copeptin can be determined by the so-called assayHomogeneous assay of type, using so-calledThe technology is carried out.

The preferred embodiment of the present invention discloses the use of the antibodies generated against the above-described peptides 0413-pAK and 0417-pAK, especially for sandwich type 2-site immunoassays. Another preferred embodiment of the invention discloses the use of such antibodies for detecting and determining the concentration of the molecules of the invention, in particular copeptin, in a variety of bodily fluids and other biological materials. Copeptin can be detected in preferred embodiments at concentrations above 50pg/ml in body fluids (FIG. 1).

In one embodiment the invention is based on and uses the long term stability of ex vivo copeptin found in plasma and serum (table 2). Copeptin content in plasma and serum was surprisingly stable even after 2 days of storage at room temperature. Copeptin is therefore more suitable than vasopressin for diagnostic purposes.

A preferred embodiment of the invention discloses the use of antibodies raised against PLAY17 and PATV17 for detecting copeptin in healthy individuals, patients with sepsis, cardiac infarction, and elevated arterial blood pressure (FIG. 2), and for determining the severity of chronic or Congestive Heart Failure (CHF) (FIG. 4).

The invention additionally allows determination of the presence and stability of the molecules of the invention, especially copeptin, in body fluids and determination of the difference in peptide concentration in healthy control individuals and patients with various diseases, including those mentioned above (FIG. 2; FIG. 4). The median value for healthy control individuals was about 13 pg/ml.

The present invention further discloses significant changes in the concentration of the bodily fluid biomarker copeptin in bodily fluids under disease states including those mentioned above.

The preferred embodiments of the present invention are based on the following surprising findings: the copeptin concentration changes were very significant, i.e. about a 10-fold increase, in the plasma of patients with sepsis (median 150, 5pg/ml) and myocardial infarction (median 129, 5pg/ml), and about a 35-fold increase in patients with elevated arterial blood pressure (median 459, 5 pg/ml).

The copeptin content measured in CHF patients correlates well with disease severity, which is usually assessed using the New York Heart Association (NYHA) functional classification system, where NYHA classes I to IV correspond to the following typical functional abilities: NYHA class I-asymptomatic; NYHA class II-symptoms of moderate effort (intervention); NYHA class III-with minimal effort symptoms; NYHA class IV-symptoms at rest (dyspnea). Copeptin content was determined in a study in plasma samples from a total of 348CHF patients (25 NYHA class I; 124 NYHA class II; 127 NYHA class III; 72 NYHA class IV; see Table 1)) with a clear trend for the median value of the different classes (see Table 1 below).

The invention also provides diagnostic methods, kits and assays for the above-mentioned diseases using one or more antibodies, in particular copeptin.

Drawings

FIG. 1 shows a standard curve of a sandwich immunoassay for copeptin immunoreactivity using peptide PAY33 as a standard substance.

FIG. 2 shows the copeptin immunoreactive concentrations in samples of healthy subjects and different groups of patients (sepsis, heart infarction and elevated arterial blood pressure).

FIG. 3 shows the amino acid sequence of vasopressin pro-hormone (one letter code; see also SEQ ID NO: 4).

FIG. 4 shows the copeptin immunoreactive concentration in a sample of a CHF (chronic heart failure) patient classified according to the NYHA classification system.

Materials, methods and measurements

Example 1

Synthesis of peptides

The peptides were synthesized according to standard methods known to those skilled in the art and their quality was controlled by mass spectrometry and reverse phase HPLC control and lyophilized into aliquots (Jerini AG, Berlin, Germany). The amino acid sequence of the peptides is as follows (numbers refer to the corresponding positions in the prepro-neurotensin 2-copeptin-precursor (positions 132-:

PATV17 (132-147+ N-terminal cysteine residue): CATQLDGPAGALLLRLV [ sequence ID 1],

PLAY17 (149-164+ N-terminal cysteine residue): CLAGAPEPFEPAQPDAY [ sequence ID 2],

the standard peptide PAY33 (132-164) ATQLDGPAGALLLRLVQLAGAPEPFEPAQPDAY [ sequence ID 3 ].

Example 2

Conjugation and immunization

The peptides of sequence ID 1-2 were linked to the carrier protein KLH (keyhole limpet hemocyanin) via MBS (-maleimidobenzoyl-N-hydroxysuccinimide maleate) according to the protocol described in PIERCE, Rockford, IL, USA for "NHS-ester-maleimide crosslinker". Sheep were immunized and received 100 μ g of conjugate (μ g according to the amount of peptide in the conjugate) followed by 50 μ g of conjugate every four weeks (an amount related to the amount of peptide in the conjugate). 700ml of blood was drawn from each sheep every four weeks starting at month 4 after immunization and antisera were obtained by centrifugation. Conjugation, immunization and production of antisera were carried out according to the method of MicroPharm, Carmerthenshire, UK.

Example 3

Purification of antibodies

Polyclonal antibodies from sheep were purified by ligand-specific affinity purification. For this step the peptides PATV17 and PLAY17 were linked to a sulfoLink-gel supplied by Pierce (Boston, USA). The binding takes place according to the scheme of Pierce. 5mg of peptide was added per 5ml of gel.

In summary, the column was washed three times with 10ml of elution buffer (50mM citric acid, pH 2.2) and binding buffer (100mM sodium phosphate, 0.1% Tween, pH 6.8). 100ml of sheep antiserum was filtered through a 0.2 μm diameter filter and then added to the column material, which had been transferred from the column into a beaker containing 10ml of binding buffer. The material was incubated overnight at room temperature under gentle rotation. The material was transferred to an empty column (NAP 25, Pharmacia, emptied). The eluate was discarded. The column was subsequently washed with 250ml of protein-free binding buffer (protein content in the washed eluate < 0.02A 280 nm). Elution buffer was added to the wash column and 1ml fractions were collected. The protein content of each fraction was determined by BCA method (according to protocol of PIERCE, Rockford, IL, USA). Fractions with a protein content > 0.8mg/ml were combined. 39mg of anti-PATV 17 antibody 0413-pAk and 103mg of anti-PLAY 17 antibody 0417-pAk were obtained after determination of the protein content.

Example 4

Marking

anti-PLAY 17 antibody 0417-pAk was treated as follows: 500. mu.l of the affinity-purified antibody thus produced was buffered again in 1ml of 100mM potassium phosphate buffer (pH 8.0) via NAP-5 gel filtration column (Pharmacia) according to the Pharmacia protocol. The protein concentration in the antibody solution was 1.5 mg/ml.

For labeling with chemiluminescent markers, 10. mu.l of MA 70-Akridinium-NHS-ester (1 mg/ml; Hoechst Behring) was added to 67. mu.l of the antibody solution and incubated for 15 minutes at room temperature. Then 423. mu.l of 1M glycine were added and incubated for 10 minutes. The solution was buffered again in 1ml of solvent A (50mM potassium phosphate, 100mM NaCl, pH 7.4) using a NAP-5 gel filtration column according to the protocol of Pharmacia. For final clearance of unbound markers gel filtration HPLC (column: Waters Protein Pak SW300) was used. The sample was added and chromatographed with solvent A at a flow rate of 1 ml/min. The flow was continuously monitored with a UV meter at wavelengths of 280 and 368nm to determine the extent of labeling. The absorption coefficient of the labeled antibody was 368/280nm, which was 0.1. The monomeric antibody-containing fractions (retention time 8-10 min) were collected and taken up in 3ml of 100mM sodium phosphate, 150mM NaCl, 5% bovine serum albumin, 0.1% sodium azide, pH 7.4).

Example 5

Coupling of

The anti-PATV 17 antibody 0413-pAk was immobilized on a radiation-treated 5ml polystyrene tube (Greiner, Germany). For this method the antibody solution was diluted with 50mM Tris, 100mM NaCl, pH 7.8 to a protein concentration of 6.6. mu.g/ml. Pipette 300. mu.l of the diluted protein solution per tube. These solutions were incubated at 22 ℃ for 20 hours and the solutions were removed. Then 4.2ml of 10mM sodium phosphate, 2% Karion FP, 0.3% bovine serum albumin, pH 6.5 solution was added to each tube. After 20 hours the solution was removed and the tubes were dried in a vacuum desiccator.

Example 6

Immunoassay

The following assay buffers were used: 100mM sodium phosphate, 150mM NaCl, 5% bovine serum albumin, 0.1% nonspecific sheep IgG, 0.1% sodium azide, pH 7.4.

The copeptin concentration of EDTA-plasma was determined in healthy individuals and in patients with various diseases/diseases mentioned above, especially heart diseases and diseases of the circulatory system.

A chemically synthesized peptide (peptide PAY33) corresponding to the 132-164 position of the vasopressin-neurotensin 2-copeptin precursor was used as a standard substance. The standard was diluted with standard horse serum (Sigma).

Mu.l of standard substance or sample and 100. mu.l of assay buffer are pipetted into the test tube. Each tube was incubated at 22 ℃ for 2 hours with gentle rotation. After washing 4 times with 1ml of washing buffer (0.1% Tween 20), the supernatant was discarded. Then 200. mu.l of assay buffer containing 1 million RLU (relative light units) of MA 70-labeled antibody was added, followed by incubation at 22 ℃ for 2 hours under gentle rotation. After 4 washes with 1ml of wash buffer (0.1% Tween 20), the tube-bound chemiluminescence was measured by a luminometer (Berthold, LB952T, alkaline reagent Brahms AG). The concentration of the sample was determined with the software MultiCalc (spline fitting).

Example 7

Determination of copeptin concentration

The term copeptin immunoreactivity describes the amount of substrate detected by an imaged sandwich immunoassay. The sandwich immunoassay uses elevated antibodies against the vasopressin-neurotensin 2-copeptin-precursor at positions 132-147 and 149-164 for the detection of the substrate. A typical standard curve for the imaging assay is depicted in figure 1. The assay allows quantification of copeptin immunoreactivity in plasma or serum at concentrations above 50 pg/ml.

Example 8

Concentrations of copeptin immunoreactivity in healthy individuals and disease states

Serum and plasma were analyzed from healthy subjects and patients suffering from various diseases including sepsis, cardiac infarction and elevated arterial blood pressure (fig. 2). Copeptin immunoreactivity was determined. Copeptin immunoreactivity was surprisingly increased in disease states compared to healthy individuals. Healthy subjects showed a median of about 13pg/ml, sepsis patients a median of about 150pg/ml, myocardial infarction patients a median of about 129pg/ml, and patients with elevated arterial blood pressure a median of about 459 pg/ml.

Example 9

Copeptin immune responses in Chronic Heart Failure (CHF) patients of NYHA class I to I V Stress concentration

Copeptin content was determined in serum and plasma samples from a total of 348CHF patients (25 as NYHA class I; 124 as NYHA class II; 127 as NYHA class III; 72 as NYHA class IV; see Table 1) using the assay described above. The results are shown in graphical form in figure 4. It can be seen that the median values of copeptin concentrations (pg/ml) of the different classes show a clear increasing trend: the median value for NYHA class I patients was found to be 20.30pg/ml, class II 33.25pg/ml, class III 49.60pg/ml, class IV 85.80pg/ml (see statistics in Table 1 below).

TABLE 1

	NYHA I	NYHA II	NYHA III	NYHA IV
					The number of people of all kinds	25	124	127	72
Median value	20.30	33.25	49.60	85.80
					Mean value	27.00	45.32	63.91	184.7
Mean value of less than 95% CI	17.45	38.79	55.29	118.9
					Higher than 95% CMean value of I	36.56	51.86	72.54	250.5

CI-confidence interval

The severity of CHF was found to be closely related to copeptin content in plasma, making copeptin a biomarker candidate for use in diagnosis (positive or negative diagnosis) of CHF, monitoring of the course and progression of CHF, and monitoring and control of CHF therapy. In addition, given the current effectiveness of vasopressin receptor antagonists in attempts to evaluate the treatment of heart failure [27], determining copeptin in serum or plasma samples of heart failure patients may allow to identify such patients that would benefit more than other patients treated with vasopressin receptor antagonists.

Example 10

Stability of copeptin immunoreactivity

Copeptin immunoreactivity was found to be surprisingly stable in plasma and serum (table 2). Table 2 shows the ex vivo stability of endogenous immunologically active copeptin in serum and plasma of sepsis patients.

TABLE 2

No decrease in immunoreactivity could be detected even after 2 days of storage at Room Temperature (RT).

The ex vivo stability of copeptin immunoreactivity compared to vasopressin is therefore surprisingly significantly improved.

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Claims (11)

1. Kit for the determination of copeptin comprising reagents for an immunoassay

-at least one first antibody recognizing a first amino acid sequence present as SEQ ID No. 1 or SEQ ID No. 2, and

at least one second antibody recognizing a further second amino acid sequence present as SEQ ID NO 1 or SEQ ID NO 2,

wherein at least one of the first or second antibodies carries a detectable marker.

2. The kit according to claim 1, wherein the antibody is a polyclonal and/or monoclonal antibody.

3. The kit according to claim 1, further comprising peptides for use as standards and for calibration purposes.

4. The kit according to claim 3, wherein the peptide has the amino acid sequence of SEQ ID NO 3.

5. A kit according to claim 1, wherein said kit is for determining the amount of copeptin and/or a pathophysiologically present copeptin precursor, splice variant, fragment or post-translationally modified form showing copeptin immunoreactivity in a body fluid sample.

6. The kit according to claim 5, wherein the body fluid sample is selected from the group consisting of serum, plasma, blood or cerebrospinal fluid CSF.

7. The kit according to claim 1, wherein one of the first or second antibodies is immobilized on a surface.

8. The kit according to any one of claims 1 to 6, wherein the immunoassay is a homogeneous immunoassay.

9. The kit according to any one of claims 1 to 7, said immunoassay being a heterogeneous immunoassay using a first immobilized specific antibody and a second solubilized specific antibody carrying a detectable marker or being selectively labeled by reaction with a labeled marker molecule.

10. Use of an antibody recognizing the amino acid sequences present as SEQ ID NO 1 and SEQ ID NO 2 for the preparation of a kit according to any one of claims 1 to 9.

11. Use according to claim 10, for diagnosing or monitoring the presence and/or the course and/or the severity and/or the prognosis of a condition associated with or caused by a non-physiological change in vasopressin released from the neuropituitary, said condition being selected from sepsis, heart infarction, chronic heart failure and arterial hypertension.