JPH08175999A - Filter for removing leukocyte - Google Patents

Abstract

PURPOSE: To obtain a leukocyte-separating filter capable of highly efficiently removing leukocytes and blood aggregates in blood and good in the recovery and filtration speed of erythrocytes. CONSTITUTION: In the leukocyte-separating filter, a diffusion sheet 4 for separating a blood inlet side from a blood outlet side and intermediate members 5 are disposed between fibrous material layers 6 and 7 in a housing 1 having a blood inlet 2 and a blood outlet 3, and the occupation proportion of the areas of the diffusion sheet 4 and the intermediate members 5 to the filtration area is 40-80% in the center of the filtration area.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a filter for removing leukocytes in blood and body fluids.

[0002]

2. Description of the Related Art It is widely known that leukocyte-removing blood products are transfused to prevent non-hemolytic fever reactions that show symptoms such as fever, chills, and scars in the treatment of frequent transfusion patients. Has been.

Normally, there are 10 ⁹ white blood cells in 400 cc of blood, and patients transfused with the blood have anti-H
It produces LA antibody and exhibits a non-hemolytic fever reaction. When 99.9% of leukocytes in the blood are removed, the leukocyte count is lowered to the level of 10 ^{6 in the} above unit dose, and the non-hemolytic fever reaction is prevented.

Further, as it has been revealed that the side effect after blood transfusion is due to the alloimmune reaction caused by leukocytes in blood products, leukocytes in the blood are removed by 99.9% or more in order to prevent the induction of alloimmune. Is required.

There are two methods for removing leukocytes: a method by centrifugation utilizing the difference in specific gravity of blood components and a method using a leukocyte removal filter. Since a high leukocyte removal rate can be obtained by a simple operation, the leukocyte removal filter can be obtained. The use of is widespread.

The leukocyte removal filter is a non-woven fabric made of hydrophobic ultrafine fibers such as polyester or a porous material filled in a housing, and leukocytes are removed by being trapped and adsorbed on the fiber surface.

In order to remove leukocytes at a high rate, it is preferable to increase the fiber surface area in the fiber assembly, and if the volume of the non-woven fabric is the same, the non-woven fabric having a smaller fiber diameter has a smaller fiber surface area. In a non-woven fabric having the same fiber diameter, the larger the bulk density and the smaller the fiber spacing, the larger the fiber surface area.

In blood products, blood cell components such as red blood cells, white blood cells, and platelets, plasma, and agglomerates are present. In order to reduce clogging of the ultrafine fiber nonwoven fabric due to the agglomerates, first, the agglomerates having a large diameter are pre-treated. A filter having a two-layer structure in which a filter layer removes leukocytes and then leukocytes are removed by a main filter layer has been proposed. This aims to reduce the clogging of the main filter by arranging the fiber aggregate having a large fiber diameter in the upper layer of the fiber aggregate having a small fiber diameter, but an aggregate of 10 to 20 μm of the same size as the white blood cells. It is not enough to remove blood and has a drawback that blood having a high hematocrit (Ht) value has a long filtration time.

Further, the pre-filter layer is reinforced so as to be 3-4.
It has been proposed that a layer structure can prevent the main filter layer from being blocked (Japanese Patent Laid-Open No. 1-236064). This limits the range of the fiber diameter and the fiber interval of each layer, and is captured from the one having a large diameter of the aggregate, and the frequency of clogging the main filter layer is reduced as compared with the two-layer structure. However, since blood flowing from a certain direction passes through the same place on the filter surface, as many aggregates are removed, the first layer is gradually clogged and finally the flow rate of the entire layer is reduced. Therefore, the inventor
As a result of investigating a method that does not reduce the flow rate of the entire layer even if there is a part where the layer is clogged, it can be said that by arranging the support between the first layer and the second layer, the clogging is small and the flow rate is small. The invention of Japanese Patent Application No. 5-243668 was reached.
However, the support provided between the first layer and the second layer forms a space between the first layer and the second layer to improve the flow, but the flow direction of blood is constant, so the flow is not diffused. However, it was by no means sufficient as a measure to prevent filter clogging.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the above problems and provide a leukocyte removal filter which efficiently removes leukocytes in blood and has a good red blood cell recovery rate and filtration time. .

[0011]

SUMMARY OF THE INVENTION The present invention is a leukocyte removal filter having a housing having a blood inlet and a blood outlet filled with a fibrous substance, wherein the housing has a blood inflow side and a blood outflow side. A leukocyte removal filter in which a diffusion sheet and an intermediate that are separated from each other are arranged between fibrous material layers, and the ratio of the diffusion sheet and the intermediate to the filtration area is 40 to 80% of the central portion of the filtration surface. Use as a summary.

In the present invention, the fibrous substance is an aggregate of fibers having a large number of continuous shared spaces in which the fibers are entangled with each other, and examples thereof include a porous body, a non-woven fabric, a woven fabric, and a mesh. To be

As the fibrous substance, it is preferable to use hydrophobic fibers such as polyester, polypropylene, polyethylene and polytetrafluoroethylene.

The fiber diameter of the fibrous substance is preferably in the range of 1 to 40 μm. When the fiber diameter is less than 1 μm, the fiber spacing per unit area of the fibrous substance becomes small, and the filtration resistance becomes large, which is not preferable. On the other hand, if the fiber diameter exceeds 40 μ, the volume of the fiber becomes large and the amount of blood adsorbed to the fibrous substance becomes large, which is not preferable.

The fibrous substance preferably has a pre-filter layer for removing aggregates larger than white blood cells and a main filter layer for removing white blood cells. A fibrous substance having a fiber diameter of 10 to 40 μ is used for the pre-filter layer. When the fiber diameter exceeds 40μ, the blood aggregate is not removed, and the fiber diameter is 1
If it is less than 0, the blood aggregates will be clogged, which is not preferable. A fibrous substance having a fiber diameter of less than 10 μ is used for the main filter layer. This is because leukocytes are not removed unless the fiber diameter is less than 10 μm. Generally, leukocytes have a higher removal rate as the fiber diameter becomes smaller. Therefore, it is preferable to dispose the pre-filter layer on the blood inflow side and the main filter layer on the blood outflow side.

In the present invention, a diffusion sheet is sandwiched between the prefilter of fibrous material and the main filter layer. The diffusion sheet separates the inside of the housing into a blood inflow side and a blood outflow side, and the filter layers are used for accurately collecting target substances such as blood aggregates and white blood cells in each layer.

In the present invention, the diffusion sheet is a hydrophobic sheet made of polyester, polypropylene, polyethylene, polytetrafluoroethylene or the like. The characteristic of the diffusion sheet may be one that does not allow liquid to pass through. The thickness of the diffusion sheet is preferably in the range of 100 to 1000μ.

Since the diffusion sheet has a role of diffusing the blood flow concentrated in the central portion of the filtration area to the end portion of the filter, the central portion of the filtration surface is covered by 40 to 80% and the blood inlet and the blood outlet are vertically arranged. In view of the above, it is preferable to arrange the filter so that the filter surface is reduced in the left and right directions. If it is less than 40%, it is difficult to diffuse blood flow, and if it exceeds 80%, the filtration rate is lowered, which is not preferable. The filtration area means the area of the filter layer expanded in the housing.

In the present invention, by arranging the intermediates above and below the diffusion sheet, a space is formed between the fibrous substance and the diffusion sheet, and an effect of preventing the fibrous substance from adhering to the surface of the diffusion sheet is obtained.

In the present invention, it is preferable to use hydrophobic fibers such as polyester, polypropylene, polyethylene and polytetrafluoroethylene for the intermediate body made of cloth. Any intermediate may be used as long as it does not impede blood flow, and woven cloth, mesh, sponge or the like having a pore size through which blood components can pass can be used. The thickness of the intermediate is 200-1
It is preferably in the range of 500μ. If it is less than 200 μ, it is difficult to form a space between the fibrous substance and the diffusion sheet, and if it exceeds 1500 μ, the amount of blood staying in the cloth increases, which is not preferable.

[0021]

[Effect] In the conventional method, the blood flow direction is kept constant and the aggregates are captured and removed step by step. Therefore, there is a drawback that the blood flow direction is not diffused and some clogging occurs. By arranging the diffusion sheet and the intermediate body in an appropriate size between the fibrous substances, the blood that has flowed in from the blood inlet is diffused by the diffusion sheet while preserving relatively large aggregates in the blood. After removal with a filter, the remaining white blood cells and aggregates similar to it move from both sides of the diffusion sheet and are removed by the main filter, so the entire surface of the filter is effectively used,
Clogging does not occur easily and the loss of blood flow is minimized, and the removal rate of leukocytes and aggregates in blood is high.

[0022]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing an example of a leukocyte removal filter according to the present invention. 2 is a sectional view taken along line AA of FIG. FIG. 3 is a sectional view taken along line BB of FIG. In the following examples and comparative examples, the leukocyte removal rate and red blood cell recovery rate, which are evaluation items, were calculated by the following formula. Leukocyte removal rate = {1- (white blood cell count after filtration) / (white blood cell count before filtration)} × 100 Red blood cell recovery rate = (Ht value after filtration) / (Ht value before filtration) ×
100

In FIGS. 1 and 3, a flat container made of polycarbonate having a filtration area of 45 cm 2 and a capacity of 40 cc was prepared as the housing 1 for filling the fibrous substance. The fibrous substance pre-filter 6 has an average fiber diameter of 10 μm, a filling amount of 1.3 g, and a bulk density of 0.14 g.
A polyester non-woven fabric having a fiber diameter of 1.6 μm, a filling amount of 2.4 g, and a bulk density of 0.12 g / cubic centimeter was used as the main filter 7.

A polyethylene film having a thickness of 500 μ is used as the diffusion sheet 4, and a longitudinal density is 10 fibers / c as the intermediate body 5.
A 800-μm-thick polyester mesh made of plain weave having a m and a lateral density of 8 filaments / cm was used.

[Embodiment] The prefilter 6, the main filter 7, the diffusion sheet 4 and the intermediate 5 are placed 6-5 from the blood inlet 2 of the housing 1 toward the blood outlet 3.
The experiment was performed using the ones arranged in the order of -4-5-7. At this time, the diffusion sheet 4 and the intermediate body 5 were arranged so as to cover the central portion of the filtration area by 70% as shown in FIG.
One unit of concentrated red blood cells derived from whole blood 400 within 3 days after blood collection was filled into the housing 1 without priming and filtered with a head difference of 1 m. The white blood cell count and Ht value before and after filtration were measured, and the white blood cell removal rate and red blood cell recovery rate were calculated by the above formula. Further, the time from immediately after filling with blood until the blood bag became empty was measured as the filtration time. The results are shown in Table 1.

[0026]

[Table 1]

Comparative Example 1 Diffusion sheet 4 and intermediate 5
A filter having a two-layer structure in which the pre-filter 6 and the main filter 7 are arranged in the order of 6-7 from the blood inlet 2 of the housing 1 toward the blood outlet 3 in the same configuration as that of the embodiment except not using Experimented with. One unit of concentrated red blood cells derived from whole blood 400 within 3 days after blood collection was filled into the housing 1 without priming, filtered with a head difference of 1 m, and the filtration time and leukocyte removal rate were the same as in Example.
The red blood cell removal rate was measured and calculated. Table 2 shows the results.

[0028]

[Table 2]

[Comparative Example 2] The same diffusion sheet 4 and intermediate 5 as those in the example were used, and the arrangement area of the diffusion sheet 4 in FIG. 2 was set to 30%. The pre-filter 6, the main filter 7, the diffusion sheet 4 and the intermediate body 5 are moved from the blood inlet 2 of the housing 1 toward the blood outlet 3 6-5-4-5-
Experiments were carried out using those arranged in the order of 7. One unit of concentrated red blood cells derived from whole blood 400 within 3 days after blood collection was filled into the housing 1 without priming and filtered with a head difference of 1 m, and the filtration time, leukocyte removal rate, and red blood cell removal rate were determined in the same manner as in the example. Measured and calculated. The results are shown in Table 3.

[0030]

[Table 3]

[Comparative Example 3] The same diffusion sheet 4 and intermediate body 5 as in the example were used, and the arrangement area of the diffusion sheet 4 in FIG. 2 was set to 85%. The pre-filter 6, the main filter 7, the diffusion sheet 4 and the intermediate body 5 are moved from the blood inlet 2 of the housing 1 toward the blood outlet 3 6-5-4-5-7.
Experiments were carried out using those arranged in the order of. One unit of concentrated red blood cells derived from whole blood 400 within 3 days after blood collection is filled into the housing 1 by non-priming and filtered with a head difference of 1 m,
The filtration time, leukocyte removal rate, and red blood cell removal rate were measured and calculated in the same manner as in the examples. The results are shown in Table 4.

[0032]

[Table 4]

From the results shown in the tables of Example 1 and Comparative Example 1, it can be seen that the use of the diffusion sheet 4 and the intermediate 5 increased the red blood cell recovery rate and shortened the filtration time. From the results shown in the tables of Comparative Examples 2 and 3, the red blood cell recovery rate decreases when the area of the diffusion sheet 4 is 40% or less, and the filtration time becomes long when the area is 80% or more. It can be seen that the ratio of the total amount of erythrocytes affects the red blood cell recovery rate and filtration time. From the above, it can be seen that the leukocyte removal filter of the present invention has the shortest filtration time and has excellent results of leukocyte removal rate and red blood cell recovery rate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a leukocyte removal filter according to the present invention.

FIG. 2 is a left-side sectional view taken along the line AA of FIG.

FIG. 2 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

 1 Housing 2 Blood Inlet 3 Blood Outlet 4 Diffusion Sheet 5 Intermediate 6 Pre-filter 7 Main Filter

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[Procedure amendment]

[Submission date] April 7, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a leukocyte removal filter according to the present invention.

FIG. 2 is a left-side sectional view taken along the line AA of FIG.

3 is a cross-sectional view taken along the line BB of FIG.

[Explanation of symbols] 1 housing 2 blood inlet 3 blood outlet 4 diffusion sheet 5 intermediate 6 prefilter 7 main filter

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Claims (2)

[Claims] 1. A leukocyte removal filter in which a fibrous substance is filled in a housing having a blood inlet and a blood outlet, and comprising a diffusion sheet and a cloth for separating the inside of the housing into a blood inflow side and a blood outflow side. A leukocyte removal filter characterized in that an intermediate is arranged between fibrous material layers. 2. The leukocyte removal according to claim 1, wherein the ratio of the diffusion sheet separating the blood inflow side and the blood outflow side and the intermediate to the filtration area accounts for 40 to 80% of the central portion of the filtration area. filter.