JPH11206876A - Filter for leucocyte separation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a filter have good removing performance and hard to be clogged, by raising the concentration of a quaternary ammonium salt toward downstream in a filter comprising specific kinds of surface fixed porous substrates with different concentrations of a quaternary ammonium salt. SOLUTION: This filter for leucocyte separation is constituted of more than three kinds of surface fixed porous substrates with different concentrations of a quaternary ammonium salt, and the concentration of the quaternary ammonium salt is raised toward downstream. The substrate 1 comprises (1) a porous substrate layer with cationization degree of 0, (2) a porous substrate layer with a cationization degree of 0.2-0.5, and (3) a porous substrate layer with a cationization degree of 0.6-1.0 and higher by 0.2-0.6 than that of (2). Further, the substrate layers are placed from the upstream side of a blood flow passage in the order of (1) the porous substrate layer with cationizaton degree of 0, (2) the porous substrate layer with cationization degree of 0.2-0.5, and (3) the porous substrate layer with cationization degree of 0.6-1.0 and higher by 0.2-0.6 than that of (2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter for separating leukocytes which has a good ability to trap leukocytes and platelets and has an excellent clogging prevention effect.

[0002]

2. Description of the Related Art The form of blood transfusion has been changing for a long time from conventional whole blood transfusion to component transfusion for transfusing only the components required by the patient, but in this component transfusion, the purity of the fractionated blood components is reduced. The challenge is how to raise the price.

[0003] Among them, in the case of concentrated red blood cells (CRC), high-purity red blood cells from which not only white blood cells but also platelets have been removed in order to suppress the production of antibodies against white blood cells and platelets and prevent transfusion side effects. Needless to say, is good.

Many attempts have been made to achieve this, such as a gravity centrifugation method utilizing the specific gravity difference of blood cells, and a filter method utilizing the action of adhesion and / or adhesion of blood cells.

[0005] Among them, the filter method is widely used because of its high leukocyte removal efficiency and simplicity of the procedure, and the structure of the filter portion is formed by packing ultra-fine fibers in a column or secondary processing into a nonwoven fabric or the like. Stuff, sponge-like 3
A typical example thereof is a continuous porous body having a three-dimensional network.

In order to remove white blood cells and platelets from concentrated red blood cells by the filter method, some contrivance is required.

[0007] That is, it is natural that the separation ability of leukocytes can be enhanced by reducing the pore size of the filter. However, if the pore size is such that platelets can be removed, clogging is likely to occur due to captured blood cells. Because
A requirement is that both white blood cells and platelets can be removed while using a filter having a relatively large pore size.

A solution is to make the zeta potential of the surface of the filter substrate positive (positive). Specifically, a cationic group, that is, a quaternary ammonium salt is added to the surface of the substrate. It is known that the platelets are preferably fixed to the substrate, whereby platelets are easily adsorbed (adhered) to the substrate and are removed.

However, in the case of such a method, the platelet adsorption ability varies depending on the degree of cationization of the base material (degree of cationization) and the platelet adsorption behavior varies due to individual differences in blood. This causes a problem due to the above.

[0010] If the degree of cationization is high, platelets are more likely to be adsorbed and removal is promoted. However, if the platelet is in a high concentration and touches a substrate with a high degree of cationization, platelets concentrate on that part and are adsorbed. As a result, the pores of the base material tend to be small, and the flow velocity tends to decrease. In an extreme case, clogging occurs, and the function as a filter cannot be achieved.

On the contrary, when the degree of cationization is low, the adsorption of platelets becomes insufficient.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems relating to a filter for removing leukocytes and platelets, and has a good removing performance and is clogged. It is intended to provide a filter that is difficult to perform.

[0013]

A first aspect of the present invention is a filter comprising at least three or more types of porous substrates having different concentrations of quaternary ammonium salts immobilized on a surface thereof, the filter being directed downstream. Wherein the quaternary ammonium salt concentration is increased.

The preferred combinations of the porous substrates of the present invention include a first porous substrate portion having a cationization degree of substantially zero, and a porous substrate having a cationization degree of 0.2 to 0.5. And a third porous substrate having a cationization degree of 0.6 to 1.0 and a 0.2 to 0.6 higher than the part.

Further, it is preferable that the combination of the above-mentioned porous substrates is arranged in the order of from the upstream side of the blood flow path. With such a configuration, a good leukocyte removal rate and a good platelet removal rate are obtained. , And a practical flow rate can be stably obtained.

As the porous substrate used in the present invention, polyethylene, polypropylene, polyurethane, polyester, polyamide, polysulfone, polyethersulfone, polyamide polyether block copolymer, polyester polyether block copolymer, ethylene vinyl alcohol copolymer and the like are used as filters. And a porous body, a flat membrane, a nonwoven fabric, a woven fabric, a knitted fabric or a composite thereof.

Particularly preferred organic polymers are polyurethane, polyester, polyamide or ethylene vinyl alcohol copolymer, and the shape is preferably a three-dimensional network porous body or nonwoven fabric.

In consideration of the leukocyte or platelet removal rate and the flow rate at the time of filtration, a filter having a most frequent pore diameter of 1 to 7 microns, more preferably 2 to 6 microns is preferred.

Next, in the present invention, "the surface-fixed fourth
The term "quaternary ammonium salt" means a quaternary ammonium salt fixed to the porous substrate in the form of a chemical bond or a coat, and is fixed by, for example, the following method.

At least one type of functional group (acid halide group, isocyanate group, epoxy group, etc.) is introduced into the surface of the porous substrate by plasma-initiated polymerization, and a site capable of reacting with these functional groups (amino group, carboxyl group, etc.). A quaternary ammonium salt compound having a hydroxyl group or a hydroxyl group). As a typical example, glycidyl acrylate is subjected to surface graft polymerization (in which an epoxy group is introduced), and then the following general formula (1)

[0021]

[Chemical formula 1]

There is a method of reacting with the compound of the formula (1).

A method of fixing a quaternary ammonium salt of an organosilicone type to the surface of a porous substrate. A typical example is the following general formula (2)

[0024]

[Chemical formula 2]

There is a method in which a porous substrate is treated with an aqueous solution containing a sulfate surfactant (for example, sodium lauryl sulfate).

As described at the outset, the leukocyte separation filter of the present invention is composed of at least three or more types of porous substrates having different quaternary ammonium salts fixed on the surface.

Here, the type does not necessarily mean the number of sheets. The gist of the present invention is a constitution comprising at least three or more types having different degrees of cationization depending on the concentration of the quaternary ammonium salt, in other words, three or more layers.

For example, a filter composed of six polyurethane porous sheets, wherein the sheet is composed of three layers of two sheets, or a first layer composed of one sheet, a second layer composed of two sheets, and If the layer having different quaternary ammonium salt concentrations is composed of at least three or more types, such as a third layer composed of three sheets, the present invention is not limited to the above. The combination of the number of sheets in each layer is arbitrarily configured in view of the volume, the amount of filtration, and the like, and is not limited at all.

The number of quaternary ammonium salts is preferably 5 or less in consideration of practicality.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to these embodiments as long as the embodiments have the effects.

1-1. Experimental Method (Examples 1 to 4, Comparative Examples 1 to 8) Cationization treatment of filter base material: mode diameter 3 μm,
A polyurethane three-dimensional mesh-like continuous porous membrane (20 cm wide × 100 cm long) having a porosity of 90% and a thickness of 1.3 mm is
It was immersed in 8 L of an aqueous solution containing 3- (trimethoxysilyl) propyldimethyl-lauryl ammonium chloride (A) (molecular weight: 412) and sodium lauryl sulfate (B) (molecular weight: 288), and treated at 50 ° C. for 60 minutes.
Next, the product was immersed in pure water at 70 ° C., squeezed, and dried at 70 ° C. for 12 hours.

The above operations were carried out by changing the concentration of propyldimethyl-lauryl ammonium chloride (A) or sodium lauryl sulfate (B) to produce substrates having different degrees of cationization as shown in Table 1.

[0033]

[Table 1]

Measurement of the degree of cationization of the filter substrate (the amount of quaternary ammonium salt fixed): A small sample of 2 cm in diameter was sampled from the polyurethane film after the treatment, and the degree of cationization was measured based on the following method. .

The procedures (a) to (c) are performed at room temperature.

(A) Immerse the porous substrate in a phosphate buffer.

(B) The immersed substrate is immersed in a 0.025 mM trypan blue / phosphate buffer for 15 minutes.

(C) The substrate after the treatment of (b) is immersed again in a phosphate buffer for 10 minutes.

(D) The substrate after immersion is dried at 60 ° C. for 1 hour, and the reflection absorbance of the substrate surface is measured in the wavelength range of 550 to 600 nM.

Evaluation of hemofiltration performance: C _{0 to} C _{4 in} Table 1
A circular piece having a diameter of 6 cm was punched out from the substrate (film), and the substrate pieces were appropriately selected, three sheets were stacked, and filled in a dedicated module. One unit of CPD-added human erythrocyte concentrate (CRC) obtained by collecting 400 ML blood was passed through this module. The number of blood cells in the CRC before and after the filtration treatment is determined by an automatic blood cell counting device (Sysmex NE-6000, manufactured by Toa Medical Electronics Co., Ltd.) and a flow cytometer (Cyto-ACE).
150, manufactured by JASCO Corporation, the absolute number of each blood cell component was determined based on the volume of the liquid, and the leukocyte removal rate, platelet removal rate, and red blood cell recovery rate were determined from this.

1-2. Experimental Results (1) Table 2 shows the combinations of concentrated red blood cells (CRC), which easily cause clogging, as the undiluted filtration solution using the substrates shown in Table 1, and the results of filtration.

[0042]

[Table 2]

(2) Table 3 shows the combinations of concentrated red blood cells (CRC) that are difficult to capture platelets as the undiluted filtration solution using the base materials shown in Table 1 and the results of filtration.

[0044]

[Table 3]

As is clear from Tables 2 and 3, the presence of the quaternary ammonium salt improves the leukocyte removal rate and the platelet removal rate, but the filter having a high degree of cationization only causes clogging of the filter. Easy to use, low leukocyte removal rate and platelet depletion rate are insufficient with only low cationization membrane. Combination of low cationization membrane and high cationization membrane and thickening from low cationization membrane side to high cationization membrane side By flowing red blood cells, a practical flow rate can be stably maintained regardless of the type of dense red blood cells, and good removal performance can be obtained. By applying at least three or more types, it can be applied from a combination of two types with different degrees of cationization It is confirmed that the filtration time, the leukocyte removal rate and the platelet removal rate are excellent in balance regardless of the type of blood to be used.

[0046]

As described above in detail, the present invention provides at least three or more kinds of porous base materials having different concentrations of quaternary ammonium salts fixed to the surface by moving quaternary ammonium salts from the upstream side to the downstream side. It is a leukocyte removal filter having a configuration arranged to increase the concentration of salt, and has a stable flow rate and good leukocyte and platelet removal performance, so that a great contribution to medical treatment can be expected.

Claims (7)

[Claims] 1. A filter comprising at least three or more types of porous substrates having different concentrations of quaternary ammonium salts fixed on the surface, wherein the concentration of the quaternary ammonium salts is increased toward the downstream side. A leukocyte separation filter characterized by the following: 2. The base material layer according to claim 1, wherein said base material layer has a cationization degree of substantially zero, a cationization degree of 0.2 to 0.5, and a cationization degree of 0.2 to 0.5. 6-1.0
The leukocyte separation filter according to claim 1, comprising a porous substrate layer which is 0.2 to 0.6 higher in thickness. 3. The porous substrate layer wherein the degree of cationization is substantially zero from the upstream side of the blood flow path, the porous substrate layer having a degree of cationization of 0.2 to 0.5, and The leukocyte separation filter according to claim 1, wherein the porous substrate layer has a degree of cationization of 0.6 to 1.0 and 0.2 to 0.6 higher. 4. The base material is a group of polymers such as polyethylene, polypropylene, polyurethane, polyester, polyamide, polysulfone, polyethersulfone, polyamide polyether block copolymer, polyester polyether block copolymer, and ethylene vinyl alcohol copolymer. The white blood cell separation filter according to claim 1, wherein the filter is selected from the group consisting of: 5. The leukocyte separation filter according to claim 1, wherein the substrate is selected from polyurethane, polyester, polyamide, and an organic polymer of ethylene vinyl alcohol copolymer. 6. The leukocyte separation filter according to claim 1, wherein the most frequent pore diameter of the substrate is 1 to 7 μm. 7. The leukocyte separation filter according to claim 1, wherein the mode diameter of the base material is 2 to 5 μm.