Filter medium for selectively removing leucocytes

Details Filter medium for selectively removing leucocytes Filter medium for selectively removing leucocytes

1987-11-27

1990-06-26

Jones, W. Gary

Liquid purification or separation

Processes

Liquid/liquid solvent or colloidal extraction or diffusing...

210496, 2105021, 210508, 210660, 210767, B01D 3916

Patent

active

049369989

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to a fibrous filter medium for selectively removing leucocytes. More particularly, the present invention is concerned with a filter medium for selectively removing leucocytes, which is capable of efficiently removing leucocytes, with little loss of platelets, from a cell-containing suspension containing both platelets and leucocytes, represented by blood. Still more particularly, the present invention is concerned with a filter medium which is used as a filter for selectively removing leucocytes, which is capable of removing leucocytes inevitably contained in the blood to be used for, e.g., platelet transfusion while holding down the loss of platelets to the minimum, and which is also capable of removing leucocytes in the extracorporeal circulation leucocyte removal therapy for autoimmune diseases and leukemia while holding down the loss of platelets to a minimum.


DESCRIPTION OF THE PRIOR ART

In the field of blood transfusion, platelet transfusion for improving the bleeding condition of a patient fills an important position. Platelet transfusion includes fresh whole blood transfusion, fresh concentrated red cells transfusion, platelet rich plasma transfusion and platelet concentrate transfusion, and in each type of such transfusions, the blood product usually contains a considerable amount of leucocytes. If a patient repeatedly receives transfusion of blood containing leucocytes, anti-leucocyte antibodies are likely to be produced in the patient. In such a patient, an antigen-antibody reaction occurs between the leucocytes transfused along with the transfused blood and the anti-leucocyte antibodies, causing side effects such as rigor, fever, headache and nausea. It is also known that in blood transfusions, if the transfusion blood contains a large amount of lymphocytes or if the immune system of the blood recipient is weakened for some reason, the so-called GVH reaction is likely to occur. Also, it is recently known that the less the amount of the leucocytes introduced in platelet transfusion, the better the survival of the transfused platelets in the body of the patient. For the above reasons, it has been desired in the field of platelet transfusion to remove leucocytes including lymphocytes as much as possible while holding down the loss of platelets to a minimum.
Meanwhile, the therapies for autoimmune disease and leukemia by extracorporeal circulation have recently been drawing attention as new therapies free from the danger of causing side effects which are often observed in pharmacotherapy. In this case too, of course, it is desired to effectively remove leucocytes including lymphocytes while holding down the loss of platelets to a minimum.
The leucocyte removal from the blood has conventionally been conducted by a centrifugation process using a continuous type centrifuge and the like. However, this process has disadvantages in that the efficiency of leucocyte removal is not so high, that the useful components of the blood including platelets are considerably lost, and that not only expensive apparatus are needed but also cumbersome operations are required.
On the other hand, there has been proposed a filtration process which consists in removing leucocytes by adhering leucocytes onto fibers. This filtration process has advantages in that the leucocyte removal efficiency is high, the loss of erythrocytes and plasma is low, and the operation required is simple and can generally be performed at low cost.
Takenaka et al. disclosed that a filter comprising a mass of fibers having an average diameter of 3 to 10 .mu.m can efficiently entrap leucocytes (see U.S. Pat. No. 4,330,410, British Patent No. 2018151B, French Patent No. 7905629, and West German Patent No. 2908722). Watanabe et al. disclosed that a non-woven fabric filter comprised of fibers having an average diameter of less than 3 .mu.m not only has a high leucocyte' removal efficiency but also can attain an increased rate of treating blood (see Japanese Patent Application Laid-open Specifica

REFERENCES:
patent: 4330410 (1982-05-01), Takenaka et al.
patent: 4416777 (1983-11-01), Kuroda et al.
patent: 4617124 (1986-10-01), Pall et al.
patent: 4620932 (1986-11-01), Howery
patent: 4701267 (1987-10-01), Watanabe et al.
Biomaterials, vol. 6, Nov. 1985, pp. 409-415, Butterworth & Co., GB, N. Yui et al., "Reversibility of Granulocyte Adhesion Using Polyamine-grafted Nylon-6 as a New Column Substrate for Granulocyte Separation".
Derwent Abstract 85-193,172, "Synthetic High Polymer for Artificial Organs Production".
Chemical Abstracts, vol. 97, No. 2, Jul. 12, 1982, p. 365, K. Sanui et al, "Effect of Microphase Separated Structure in Platelets Adhesion on Graft Polyamides".

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