A filter for removing leukocytes

Abstract

The application provides a leukocyte-removing filter and relates to the technical field of whole blood filtration. The filter element is modified by using agarose, chitosan and polyethylene glycol, so that the flowability of red blood cells when passing through the filter hole of the filter element is improved. Meanwhile, the modified filter element is applied to a secondary filter and used as a small-pore filter, so that the whole blood is filtered by using the drop, the damage to the red blood cell tissue in the filtering process is reduced while the leukocyte filtering effect is ensured, and the whole blood quality is improved. Experimental results show that, by using the leukocyte-removing filter provided by the application to filter the whole blood, the residual leukocyte content of each unit after filtration is as low as 10 5 orders of magnitude, and the increase ratio of FHb after filtration is as low as 66%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of whole blood filtration, in particular to a filter for filtering leukocytes. BACKGROUND

[0002] Whole blood is a mixture formed by collecting blood in the body into a blood collection bag, including red blood cells, white blood cells, platelets and plasma. White blood cells play a basic role in the body's immune system, but if blood components containing white blood cells are transfused to patients, many side effects will occur. Therefore, it is necessary to remove white blood cells from whole blood to obtain safe and high-quality whole blood. At present, there are washing method, filtration method and the like for removing white blood cells from whole blood, among which the filtration method is simple to operate and has good filtration effect, and is a widely used method for filtering leukocytes. The filtration method uses the principle of mechanical blocking and adsorption to intercept white blood cells. Whole blood passes through the filter under the action of its own gravity, and white blood cells are intercepted in the filter. Red blood cells with smooth surface and strong deformation ability can pass through the filter.

[0003] In the process of filtering leukocytes, although red blood cells can pass through the filter hole by deformation, they will inevitably be damaged due to mechanical friction with the filter fibers, thereby affecting the quality of whole blood components. Therefore, it is of great significance to explore how to ensure the leukocyte filtration rate and reduce the damage to red blood cells during whole blood filtration. SUMMARY

[0004] Therefore, the present application provides a filter for filtering leukocytes. The filter provided by the present application can protect red blood cells on the basis of ensuring the leukocyte filtration rate, reduce the damage to red blood cells caused by mechanical friction during filtration, and improve the safety and quality of whole blood.

[0005] The filter for filtering leukocytes provided by the present application comprises:

[0006] a liquid inlet pipe for conveying whole blood;

[0007] a large-pore filtration cavity connected to the liquid inlet pipe outlet;

[0008] a small-pore filtration cavity connected to the outlet of the large-pore filtration cavity;

[0009] a liquid outlet pipe connected to the outlet of the small-pore filtration cavity;

[0010] wherein the large-pore filtration cavity is provided with a first filter core; and the small-pore filtration cavity is provided with a second filter core;

[0011] The second filter core comprises a second filter core body and a surface modification layer formed on the surface of the second filter core body; and the surface modification layer comprises agarose, chitosan and polyethylene glycol.

[0012] In some specific implementations, the mass ratio of agarose, chitosan and polyethylene glycol is (15-20): (10-20): (5-15).

[0013] In some specific implementations, the mass ratio of the surface modification layer in the second filter element to the second filter element body is (5-20): (80-95).

[0014] In some specific implementations, the molecular weight of the polyethylene glycol is 200-400.

[0015] In some specific implementations, the small-pore filter cavity includes a second filter cavity and a third filter cavity, and the second filter cavity and the third filter cavity are connected in parallel.

[0016] In some specific implementations, the first filter element includes multiple layers of first non-woven fabric; the average pore size of the first non-woven fabric is 10-15 μm;

[0017] The second filter core body includes multiple layers of second non-woven fabric, and the average pore size of the second non-woven fabric is 3-6 μm.

[0018] In some specific implementations, the number of layers of the multi-layer first non-woven fabric and the multi-layer second non-woven fabric is independently selected from 5 to 30 layers.

[0019] In some specific implementations, the materials of the first non-woven fabric and the second non-woven fabric are independently selected from at least one of polyethylene terephthalate, polybutylene terephthalate, polyurethane, polymethacrylate, polyacrylate, polyacrylonitrile, polyvinyl acetal, polyester, polyamide, polysulfone, polystyrene, polyethylene, polypropylene, cellulose and cellulose acetate.

[0020] In some specific implementations, the fiber diameters of the first non-woven fabric and the second non-woven fabric are independently selected from 0.3 to 3.0 μm.

[0021] In some specific implementations, the liquid outlet of the large-pore filter cavity further includes a liquid balancing component, and the liquid balancing component is connected to the liquid inlet of the small-pore filter cavity.

[0022] The present invention provides a filter for removing white blood cells. The filter provided by the present invention combines a large-pore filter cavity with a small-pore filter cavity, and at the same time, the filter material of the small-pore filter cavity is surface-modified using agarose, chitosan, and polyethylene glycol, thereby improving the fluidity of red blood cells when passing through the filter pores of the filter element. While ensuring the white blood cell filtration effect, it also reduces the damage to the red blood cell tissue during the filtration process, thereby improving the quality of whole blood. Experimental results show that when the filter and method for removing white blood cells provided by the present invention are used to filter whole blood, the residual white blood cell content per unit after filtration is as low as 10 5 The increase in FHb after filtration was as low as 66%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a filter for removing leukocytes provided by the present invention;

[0024] Figure 2 This is a cross-sectional view of the filter cavity in the filter for removing leukocytes provided by the present invention. DETAILED DESCRIPTION

[0025] It should be understood that the expression "one or more of" includes individually each of the items recited after the expression and various combinations of two or more of the recited items, unless otherwise apparent from the context and usage. The expression "and / or" in conjunction with three or more recited items should be understood to have the same meaning, unless otherwise apparent from the context.

[0026] The terms "comprising", "having" or "containing", including their grammatical synonyms, should generally be understood as open and non-restrictive, e.g., not excluding other unrecited elements or steps, unless otherwise specifically stated or understood from the context.

[0027] It should be understood that the order of steps or the order in which certain actions are performed are not important as long as the present invention remains operable. Additionally, two or more steps or actions may be performed simultaneously.

[0028] The use of any and all examples or exemplary language, such as "such as" or "including," herein is intended merely to better illustrate the invention and does not limit the scope of the invention unless otherwise claimed. No language in this specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0029] In addition, the numerical ranges and parameters used to define the present invention are approximate values. The relevant numerical values ​​in the specific examples have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual testing methods. Therefore, unless otherwise expressly stated, it should be understood that all ranges, amounts, values, and percentages used in this disclosure are modified by the word "about." As used herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a particular value or range.

[0030] The present invention provides a filter for removing leukocytes, comprising:

[0031] Inlet tube for transporting whole blood;

[0032] A large-aperture filter chamber with a liquid inlet connected to a liquid outlet of the liquid inlet pipe;

[0033] A small-pore filter chamber with a liquid inlet connected to the liquid outlet of the large-pore filter chamber;

[0034] a liquid outlet pipe having a liquid inlet connected to a liquid outlet of the small-pore filter cavity;

[0035] Wherein, a first filter core is provided in the large-pore filter cavity; a second filter core is provided in the small-pore filter cavity;

[0036] The second filter core comprises a second filter core body and a surface modification layer formed on the surface of the second filter core body; the surface modification layer comprises agarose, chitosan and polyethylene glycol.

[0037] The inventors discovered that the primary cause of red blood cell damage during whole blood filtration is significant deformation when passing through small-pore filter elements, which can easily lead to damage. However, when passing through large-pore filter elements, the deformation is minimal, resulting in less noticeable damage. Therefore, the present invention reduces red blood cell damage during filtration and improves whole blood quality by modifying the surface of the small-pore filter elements.

[0038] See also Figure 1 , Figure 1 The schematic diagram of the structure of the filter for removing leukocytes provided by the present invention includes a liquid inlet pipe 201; a large-pore filter cavity 202; a liquid equalizing device 203; a first small-pore filter cavity 204; a second small-pore filter cavity 205, and a liquid outlet pipe 206.

[0039] In order to filter out white blood cells and other impurities as fully as possible, the filter provided by the present invention adopts the form of two-stage filtration, that is, a large-pore filter cavity and a small-pore filter cavity are used together to further improve the purity of whole blood.

[0040] The filter for removing leukocytes provided by the present invention comprises a liquid inlet tube 201 for conveying whole blood, and a liquid outlet of the liquid inlet tube 201 is connected to a liquid inlet of a large-pore filter cavity 202 .

[0041] The large-pore filter chamber 202 is used to initially trap white blood cells in the whole blood and remove some impurities and debris in the whole blood in preparation for the second filtration. The liquid outlet of the large-pore filter chamber 202 is connected to the first small-pore filter chamber 204 and the second small-pore filter chamber 205 respectively.

[0042] A first filter element is provided in the large-pore filter cavity 202. Non-woven fabric as a filter element for filtering whole blood has the advantages of high filtration efficiency, good air permeability, stable filtration performance, easy processing and molding, and relatively low cost. Therefore, in some specific implementations of the present invention, non-woven fabric is selected as the material of the first filter element. To improve the filtration effect, in some specific implementations, the first filter element is preferably a multi-layer first non-woven fabric. In some specific implementations, the number of layers of the multi-layer first non-woven fabric is 5 to 30 layers, preferably 10 to 25 layers, and more preferably 12 to 23 layers. When non-woven fabric is used as a filter element for filtering out white blood cells, if its fiber diameter is greater than 3.0 μm, the pore size of the non-woven fabric is too large and it cannot effectively filter out white blood cells; if the fiber diameter is less than 0.3 μm, the pore size of the non-woven fabric is too small, which will damage red blood cells and cause blockage. Therefore, in some specific implementations, the fiber diameter of the first non-woven fabric is 0.3~3.0μm, preferably 0.4~2.5μm, and more preferably 0.5~2.0μm. In some specific implementations, the equivalent pore size of the first non-woven fabric is 10~15μm, preferably 10~14μm. In some specific implementations, the material of the first non-woven fabric is selected from at least one of polyethylene terephthalate, polybutylene terephthalate, polyurethane, polymethacrylate, polyacrylate, polyacrylonitrile, polyvinyl acetal, polyester, polyamide, polysulfone, polystyrene, polyethylene, polypropylene, cellulose and cellulose acetate, preferably polyester, polyamide, polyacrylonitrile or polypropylene, more preferably polyethylene terephthalate, polybutylene terephthalate or polyacrylonitrile.

[0043] In order to filter the whole blood more fully, the large-pore filter chamber 202 of the present invention adopts Figure 2 The filter chamber style shown includes a filter chamber liquid inlet pipe 201, a liquid inlet chamber 202a, a filter core 202b, a liquid outlet chamber 202c, and a liquid outlet pipe 203. The liquid inlet chamber 202a and the liquid outlet chamber 202c are completely separated by the filter core 202b, thereby fully filtering the whole blood and ensuring the maximum effective area for filtering the whole blood, thereby improving the filtering efficiency. The first small-pore filter chamber and the second small-pore filter chamber adopt the same Figure 2 The same structure, the difference lies in the non-woven fabric.

[0044] The liquid balancing device 203 allows the whole blood filtered by the large-pore filter chamber 202 to enter the first small-pore filter chamber 204 and the second small-pore filter chamber 205 evenly, ensuring a steady filtration rate and preventing uneven flow of whole blood that could clog the filters. The liquid inlet of the liquid balancing device 203 is connected to the liquid outlet of the large-pore filter chamber 202, and the liquid outlet is connected to the liquid inlet of the first small-pore filter chamber 204 and the liquid inlet of the second small-pore filter chamber 205. In some specific implementations, the liquid balancing device includes multiple vertically parallel liquid balancing pipes.

[0045] The pore size of the small-pore filter cavity is relatively small. In order to ensure the filtration speed and reduce filter clogging, in some specific implementations of the invention, the first small-pore filter cavity 204 and the second small-pore filter cavity 205 are connected in parallel to serve as the small-pore filter cavity of the filter described in the present invention.

[0046] Both the first small-pore filter cavity 204 and the second small-pore filter cavity 205 are equipped with a second filter element. To reduce friction and increase the fluidity of red blood cells passing through the filter element, the second filter element of the present invention comprises a second filter element body and a surface-modified layer formed on the surface of the second filter element body. Based on the advantages of non-woven fabric as a filter material for whole blood filtration, the present invention continues to select non-woven fabric as the material for the second filter element bodies in the first and second small-pore filter cavities 204 and 205. In some specific implementations, the second filter element body is preferably composed of multiple layers of second non-woven fabric. In some specific implementations, the number of layers of the multi-layered second non-woven fabric is 5 to 30, preferably 10 to 25, and more preferably 12 to 23. In some specific implementations, the fiber diameter of the second non-woven fabric is 0.3 to 3.0 μm, preferably 0.4 to 2.5 μm, and more preferably 0.5 to 2.0 μm. In some specific implementations, the equivalent pore size of the second non-woven fabric is 3 to 6 μm, preferably 3 to 5 μm. In some specific implementations, the material of the second non-woven fabric is selected from at least one of polyethylene terephthalate, polybutylene terephthalate, polyurethane, polymethacrylate, polyacrylate, polyacrylonitrile, polyvinyl acetal, polyester, polyamide, polysulfone, polystyrene, polyethylene, polypropylene, cellulose and cellulose acetate, preferably polyester, polyamide, polyacrylonitrile or polypropylene, more preferably polyethylene terephthalate, polybutylene terephthalate or polyacrylonitrile.

[0047] Agarose and chitosan can enhance the modification effect, while polyethylene glycol can reduce the friction on the surface of the filter material fibers. Therefore, the present invention uses agarose, chitosan, and polyethylene glycol to modify the surface of the second filter element body, forming a surface modification layer on its surface. This surface modification layer has low friction and can increase the fluidity of red blood cells when passing through the non-woven fabric fibers, thereby reducing damage to red blood cell tissue during white blood cell removal. In some specific implementations, the mass ratio of agarose, chitosan, and polyethylene glycol is (15-20):(10-20):(5-15), preferably (15-20):(12-20):(5-15), and more preferably (15-20):(14-20):(6-15). In some specific implementations, the polyethylene glycol is preferably polyethylene glycol with a molecular weight of 200-400, such as PEG200, PEG300, or PEG400, more preferably PEG200. In some specific implementations, the mass ratio of the surface modification layer to the second filter element body is (5~20):(80~95), preferably (10~20):(80~95), and more preferably (10~20):(80~90).

[0048] Based on the above advantages, the present invention also selects Figure 2 The filter cavity shown is a specific style of the first small-pore filter cavity 204 and the second small-pore filter cavity 205. The specific composition is as described above, and the present invention will not be repeated here.

[0049] The whole blood is filtered through the large-pore filter chamber 202, the first small-pore filter chamber 204 and the second small-pore filter chamber 205 and then output from the liquid outlet tube 206. The liquid inlet of the liquid outlet tube 206 is connected to the liquid outlet of the first small-pore filter chamber 204 and the second small-pore filter chamber 205.

[0050] In some specific implementations of the present invention, the filtration rate of whole blood through the filter is controlled at 90-120 drops / minute, preferably 95-115 drops / minute, and more preferably 100-115 drops / minute. This is because if the filtration rate is too fast, the whole blood will not fully infiltrate the filter disc when passing through the filter element, reducing the effective filtration area of ​​the filter disc, resulting in a "flowering" phenomenon and causing excessive damage to red blood cells. If the filtration rate is too slow, it will cause clogging, affecting filtration efficiency.

[0051] In summary, the present invention provides a filter for filtering out leukocytes. The present invention first selects a combination of a large-pore filter cavity and a small-pore filter cavity as a filter, and at the same time uses agarose, chitosan and polyethylene glycol to modify the surface of the filter material of the small-pore filter cavity, thereby improving the fluidity of red blood cells when passing through the filter pores of the filter element, while ensuring the leukocyte filtration effect, reducing the damage to the red blood cell tissue during the filtration process, and improving the quality of whole blood. Experimental results show that when the filter and method for filtering out leukocytes provided by the present invention are used to filter whole blood, the residual leukocyte content per unit after filtration is as low as 10 5 The increase in FHb after filtration was as low as 66%.

[0052] The present invention will be further described below with reference to the following examples. The scope of protection of the present invention is not limited by the following examples.

[0053] Example 1

[0054] 15 layers of polyethylene terephthalate non-woven fabric are selected as the first filter element with a surface density of 42g / m 2 , thickness is 0.25mm, fiber diameter is about 2.0μm, and equivalent pore size is 10μm (tested using 3H-2000PB non-woven fabric pore size tester from Beijing Best Instrument Research Institute);

[0055] Polyethylene terephthalate non-woven fabric is selected as the second non-woven fabric with a surface density of 40g / m 2 , with a thickness of 0.22 mm, a fiber diameter of approximately 1.5 μm, and an equivalent pore size of 7 μm. A modified preparation was prepared by mixing agarose, chitosan, and polyethylene glycol PEG200 in a ratio of 15:10:8. This was sprayed onto the second non-woven fabric at a mass ratio of 10:90, followed by drying at 150°C for 5 hours. Fifteen layers of the modified second non-woven fabric were used as the second filter element.

[0056] Medical soft PVC is selected as the filter cavity material, and the first filter element and the second filter element are made by high-frequency heat-sealing and melting. Figure 2 The filter chamber shown includes a filter chamber liquid inlet pipe 201, a liquid inlet chamber 202a, a filter core 202b, a liquid outlet chamber 202, and a liquid outlet pipe 203. First, the upper and lower sections of the filter core to be used are sealed with glue, and medical soft PVC is melted on the left and right sides to form the liquid inlet chamber 202a and the liquid outlet chamber 202c, respectively. The liquid inlet chamber 202a and the liquid outlet chamber 202c are completely separated by the filter core 202b. The liquid inlet pipe 201 is installed above the liquid inlet chamber 202a, and the liquid outlet pipe 203 is installed below the liquid outlet chamber 202c.

[0057] The filter cavity of the first filter element is a large-pore filter cavity, and the filter cavity of the second filter element is a first small-pore filter cavity and a second small-pore filter cavity. The large-pore filter cavity, the first small-pore filter cavity and the second small-pore filter cavity are also made by high-frequency heat-sealing and melting. Figure 1 The filter shown includes a liquid inlet pipe 201, a large-pore filter chamber 202, a liquid equalizing device 203 provided at the liquid outlet of the large-pore filter chamber, a first small-pore filter chamber 204, a second small-pore filter chamber 205, and a liquid outlet pipe 206. The first small-pore filter chamber 204 and the second small-pore filter chamber 205 are connected in parallel and are respectively connected to the liquid equalizing device 203 and the liquid outlet pipe 206 provided at the liquid outlet of the first filter chamber. Specifically, a liquid inlet pipe 201 is provided above the large-pore filter chamber 202 for transporting whole blood, and a liquid equalizing component 203 is provided below the large-pore filter chamber 202 so that the whole blood in the large-pore filter chamber 202 is uniformly transferred to the filter chamber below. The liquid equalizing component 203 comprises multiple vertically arranged liquid equalizing pipes. The liquid inlets of the first small-pore filter chamber 204 and the second small-pore filter chamber 205 are connected to the liquid outlet of the liquid equalizing component 203. After being filtered by the first small-pore filter chamber 204 and the second small-pore filter chamber 205, the whole blood enters the liquid outlet pipe 206 and is discharged from the liquid outlet.

[0058] Example 2

[0059] The difference between this embodiment and embodiment 1 is that the ratio of agarose, chitosan, and polyethylene glycol PEG200 in the modified preparation is 20:20:10, and the spraying ratio of the modified preparation to the second non-woven fabric is 12:88. The rest is the same as in embodiment 1, and a filter is obtained.

[0060] Example 3

[0061] The difference between this embodiment and embodiment 1 is that the ratio of agarose, chitosan, and polyethylene glycol PEG200 in the modified preparation is 18:15:8, and the spraying ratio of the modified preparation to the second non-woven fabric is 15:85. The rest is the same as in embodiment 1 to obtain a filter.

[0062] Example 4

[0063] The difference between this embodiment and embodiment 1 is that the ratio of agarose, chitosan, and polyethylene glycol PEG200 in the modified preparation is 15:20:7, and the spraying ratio of the modified preparation to the second non-woven fabric is 20:80. The rest is the same as in embodiment 1 to obtain a filter.

[0064] Example 5

[0065] The difference between this embodiment and embodiment 1 is that the ratio of agarose, chitosan, and polyethylene glycol PEG200 in the modified preparation is 20:15:14, and the spraying ratio of the modified preparation to the second non-woven fabric is 13:87. The rest is the same as in embodiment 1, and a filter is obtained.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 is that the second nonwoven fabric is not modified, and the rest is the same as Example 1, to obtain a filter.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 1 is that the first nonwoven fabric and the second nonwoven fabric are both polyethylene terephthalate nonwoven fabrics, with an area density of 42 g / m 2 , a thickness of 0.25 mm, a fiber diameter of about 2.0 μm, and an average pore size of 14 μm, and the second nonwoven fabric is not modified, and the rest is the same as Example 1, to obtain a filter.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 1 is that the first nonwoven fabric and the second nonwoven fabric are both polyethylene terephthalate nonwoven fabrics, with an area density of 40 g / m 2 , a thickness of 0.22 mm, a fiber diameter of about 1.5 μm, and an average pore size of 5 μm, and the second nonwoven fabric is not modified, and the rest is the same as Example 1, to obtain a filter.

[0072] Comparative Example 4

[0073] The difference between this comparative example and Example 1 is that only polyethylene glycol PEG200 is used to modify the second nonwoven fabric, and the rest is the same as Example 1, to obtain a filter.

[0074] Comparative Example 5

[0075] The difference between this comparative example and Example 1 is that only chitosan is used to modify the second nonwoven fabric, and the rest is the same as Example 1, to obtain a filter.

[0076] Test Example 1

[0077] Ten bags of 200 ml / bag of whole blood were selected, and the collection process of the whole blood was in accordance with the requirements of the Blood Station Technical Operation Rules 2019 edition, with a collection time of ≤5 min, and the whole blood was stored in a (4±2)℃ environment after collection. The whole blood was filtered using the whole blood filters made according to Examples 1-5 and Comparative Examples 1-5 above, and the filtering speed was controlled at 110 drops / min. If the speed is too fast, the whole blood cannot fully soak the filter disc when passing through the filter core, the effective filtering area of the filter disc is reduced, which can cause the "flower disc" phenomenon and cause excessive damage to red blood cells; if the speed is too slow, it will cause blockage.

[0078] After filtration, the leukocyte content was tested, and erythrocyte destruction was characterized by testing for free hemoglobin (FHb). The instruments used were: XT-1800i blood cell counter (SYSMEX), Nageotte large-capacity leukocyte counting chamber (HAUSSER SCIENTIFIC HORSHAM, PAUSA), and plasma FHb kit (Beijing Ruierda Company).

[0079] The leukocyte content after filtration, FHb (mg / L) before filtration, and FHb (mg / L) after filtration of Examples 1 to 5 and Comparative Examples 1 to 5 were tested, and the obtained data are listed in Table 1.

[0080] Table 1 Comparison of leukocyte removal results between the examples of the present invention and the comparative examples

[0081]

[0082] *The white blood cell count before filtration is approximately 4.8×10 9 (unit)

[0083] As can be seen from Table 1, Comparative Example 1 suffers from severe red blood cell damage due to the lack of modification of the second non-woven fabric. Comparative Example 2 suffers from less red blood cell damage, but the filtration effect is substandard due to the large pore size and unsatisfactory filtration effect. Comparative Example 3 suffers from the most severe red blood cell damage despite excellent filtration effect due to the small pore size. Comparative Examples 4 and 5, which only use polyethylene glycol or chitosan for modification, still suffer from severe red blood cell damage, possibly because the modification effect of polyethylene glycol or chitosan alone on the non-woven fabric is not ideal. Based on the above test results, the present invention significantly improves the reduction of red blood cell damage when filtering out white blood cells by modifying the non-woven fabric and using it as a small-pore secondary filter.

[0084] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A filter for removing leukocytes, characterized in that: include: Inlet tube for transporting whole blood; A large-aperture filter chamber with a liquid inlet connected to a liquid outlet of the liquid inlet pipe; A small-pore filter chamber with a liquid inlet connected to the liquid outlet of the large-pore filter chamber; a liquid outlet pipe having a liquid inlet connected to a liquid outlet of the small-pore filter cavity; Wherein, a first filter element is provided in the large-pore filter cavity; a second filter element is provided in the small-pore filter cavity; the liquid outlet of the large-pore filter cavity further includes a liquid equalizing component, and the liquid equalizing component is connected to the liquid inlet of the small-pore filter cavity; The second filter core includes a second filter core body and a surface modification layer formed on the surface of the second filter core body; the components of the surface modification layer are agarose, chitosan and polyethylene glycol; the mass ratio of agarose, chitosan and polyethylene glycol is (15~20):(10~20):(5~15), and the mass ratio of the surface modification layer to the second filter core body in the second filter core is (5~20):(80~95).

2. The filter according to claim 1, characterized in that The molecular weight of the polyethylene glycol is 200-400.

3. The filter according to claim 1, characterized in that The small-pore filter cavity includes a second filter cavity and a third filter cavity connected in parallel.

4. The filter according to claim 1, characterized in that The first filter element comprises multiple layers of first non-woven fabric; the equivalent pore size of the first non-woven fabric is 10-15 μm; The second filter core body includes multiple layers of second non-woven fabric, and the equivalent pore size of the second non-woven fabric is 3-6 μm.

5. The filter according to claim 4, characterized in that The number of layers of the multi-layer first non-woven fabric and the multi-layer second non-woven fabric is independently selected from 5 to 30 layers.

6. The filter according to claim 5, characterized in that The materials of the first non-woven fabric and the second non-woven fabric are independently selected from at least one of polyethylene terephthalate, polybutylene terephthalate, polyurethane, polymethacrylate, polyacrylate, polyacrylonitrile, polyvinyl acetal, polyester, polyamide, polysulfone, polystyrene, polyethylene, polypropylene, cellulose and cellulose acetate.

7. The filter according to claim 6, characterized in that The fiber diameters of the first non-woven fabric and the second non-woven fabric are independently selected from 0.3 to 3.0 μm.

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