JPH01135514A - Filter for separating leukocytes - Google Patents

Abstract

PURPOSE:To enhance an effect in the removal of leukocytes, by using as a filter medium for a leukocyte separating filter a thermoplastic synthetic fiber whose cross-sectional shape is not circular and whose degree of deformation is at least 1:1. CONSTITUTION:As a filter medium for a leukocyte separating filter, there is used a thermoplastic synthetic fiber of polyester, polyacrylonitrile or polypropylene whose cross-sectional shape is not circular and whose degree of deformation (the ratio of the diameter of the minimum circumcircle D to the diameter of the maximum inscribed circle d) is at least 1:1 and this fiber is essentially continuous axially. This increases a fiber-to-fiber contact area likely to capture leukocytes, thus improving the removal rate of leukocytes without decreasing the filtration rate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a filter for separating leukocytes in blood, and particularly to a filter for separating leukocytes that is small and has a high leukocyte removal rate without slowing down the filtration flow rate.

(Prior art) In recent years, with the spread of soft blood bags, donated blood can be easily fractionated aseptically by centrifugation, and the form of blood transfusion has changed from the conventional whole blood transfusion to direct transfusion of components. It's here. Furthermore, with advances in hematology and immunology, there is a need to make fractionated blood components as highly pure as possible before transfusion.

However, the red blood cell fraction contains many white blood cells and platelets, and in order to increase the purity of red blood cells, gravity centrifugation methods that utilize the difference in specific gravity of blood cells, and capture materials that utilize the effects of blood cell adhesion, adhesion, etc. Methods of utilization include leukocyte separation methods using hemagglutinating agents, etc.

Among these methods, the method using a capture material is widely used because of its good leukocyte removal rate and easy operation, and the capture material includes natural cellulose, polyester, polyamide, and polyacrylonitrile.

Filters are made by filling fibers such as glass fibers in their original form or by secondary processing into nonwoven fabrics. In order to create a leukocyte removal filter with a good leukocyte removal rate by filling such fibers, it is necessary to increase the packing density, lengthen the filter layer, or reduce the diameter of the fibers to be filled. However, increasing the packing density slows down the filtration flow rate, increasing the packed bed length increases the volume of the filter column, and reducing the fiber diameter and using ultrafine fibers increases the cost. was there.

(Problems to be Solved) An object of the present invention is to solve the above-mentioned problems and provide a small leukocyte separation filter that is small and has a high leukocyte removal rate without slowing down the filtration flow rate when removing leukocytes from blood. It is something to do.

(Means for Solving the Problems) That is, the present invention provides fibers with a non-circular cross-sectional shape, a degree of irregularity of at least 1.1, and a degree of irregularity that is substantially continuous along the fiber axis direction. A leukocyte separation filter made of thermoplastic synthetic fibers, specifically, preferably has a degree of heterogeneity of 1.1 to 10, more preferably 2.5 to 8.0. More preferably, if the degree of heterogeneity is less than 1.1, sufficient leukocyte removal ability cannot be obtained.Here, the degree of heterogeneity is defined as the minimum circumscribed circle diameter and its maximum inscribed diameter in the cross section of a single fiber, as shown in Figure 2. This value is expressed as the ratio D/d to the circle diameter d. Most conventional thermoplastic synthetic fibers have a cross-sectional shape that is extremely close to a perfect circle, and the degree of irregularity is approximately 1. However, in recent years, various studies have been conducted to make the texture of synthetic fibers closer to that of natural fibers. As a result, synthetic fibers with various irregular cross-sections have been produced.

By the way, the mechanism for selectively removing only leukocytes from a blood cell suspension such as blood is thought to be that leukocytes are physically trapped between the fibers of the filter medium filled in the leukocyte separation filter. As a result of examining the irregularity of the fiber cross section and the leukocyte removal rate, the present invention was completed by finding that the leukocyte separation efficiency was higher when filled with irregularly shaped fibers than when filled with perfectly circular fibers. It is thought that the higher the degree, the more likely leukocytes are physically captured, and more voids are created due to fiber-to-fiber contact.

The thermoplastic synthetic fibers used in the present invention may be those spun from homopolymers such as polyester, polyacrylonitrile, polypropylene, polystyrene, etc., or those spun from copolymers thereof, or composite spun fibers of the above polymers. The cross-sectional shape of a synthetic fiber having a shape irregularity of at least 1.1 is shown in FIG. 3 (a
) to (h) are representative examples. In addition, the manufacturing method is, for example, by deforming the spinneret of the nozzle.

Next, the present invention will be explained in more detail with reference to Examples.

<Example> Polyester fibers of 1.5 denier and irregularity of 1.5 were packed in a column with an inner diameter of 25 mm at a packing density of 0.25 mm. The filter was filled to a packed bed length of 2811 m1 to produce a leukocyte separation filter. 20 mΩ of CPD-added human blood was allowed to flow down by gravity at a liquid head of 25 cm, and the leukocyte removal rate was determined from the number of leukocytes before and after filtration, and was found to be 97%.

Blood cell counts were performed using ELT-8 (Oats Diagnostic Systems).

<Comparative Example> A leukocyte separation filter filled with 1.5 denier polyester fibers with an almost perfect circular cross-section under the same conditions as in the example was manufactured and the same operation was performed, resulting in a leukocyte removal rate of 76%. Met.

(Effects) As mentioned above, by using fibers with irregular cross-sections as filter media for leukocyte separation filters, the contact area between the fibers, which has the possibility of capturing leukocytes, is increased.
A leukocyte separation filter having a good leukocyte removal effect can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a leukocyte separation filter of the present invention, FIG. 2 is a cross-sectional view of fibers used in the leukocyte separation filter of the present invention, and FIG. 3 is a cross-sectional view of fibers used in the leukocyte separation filter of the present invention. FIG. 3 is a cross-sectional view showing various shapes of. 1...Leukocyte separation filter 2...Housing 3...Fiber 4...Blood inlet 5...Blood outlet

Claims (1)

[Claims] 1. From thermoplastic synthetic fibers in which the cross-sectional shape of the fiber is non-circular, the degree of irregularity is at least 1.1, and the degree of irregularity is substantially continuous along the fiber axis direction. A filter for leukocyte separation. 2. The leukocyte separation filter according to claim 1, which has a degree of heterogeneity of 1.1 to 10.0. 3. The thermoplastic synthetic fiber is spun from a homopolymer such as polyester, polyacrylonitrile, polypropylene, polystyrene, etc. or a copolymer thereof, or a composite spun product of the above polymer, according to claim 1 or 2. Filter for leukocyte separation.