Evaluation of a new filter for obtaining leucocyte-poor blood

Leucocyte-poor blood plays an important role in transfusion practice. Its use minimizes the possibility of a febrile reaction following transfusion in patients who are sensitized to white cell antigens. In addition, transfusion of leucocyte-poor blood will decrease the chances of leucocyte sensitization in patients who must receive multiple transfusions. It may be desirable for use in immuno-deficient or immunologically suppressed patients who run the risk of graft vs. host disease if viable lymphocytes are transfused. The ‘Imugard IG 500 (Terumo Corporation), which utilizes the raw cotton of G. barbadense , has recently been introduced for the preparation of leucocyte-poor blood. The filter was investigated to evaluate the efficiency of leucocyte and platelet removal from packed red cells. Filtration resulted in an average white cell removal of 97%. iNo selective removal of granulocytes or lymphocytes could be demonstrated. The age of the blood at filtration and anticoagulant (CPD or ACD) appeared to have no effect on the percentage white cell removal. The average platelet removal was 77%, and removal of platelets was less efficient and less consistent than removal of leucocytes. Red cell loss averaged 5% and red cells were judged to be unaffected by the filtration process on the basis of red cell indices, ATP and 2, 3 DPG levels, methylene blue uptake and osmotic fragility curves. This filtration technique has a number of advantages: it is simple, relatively inexpensive, takes less than 1 h to perform, requires no special ancillary equipment, results in a high red cell recovery with no overt damage to red cells, and the leucocyte removal is excellent in comparison with other techniques. Removal of platelet-rich plasma from the red cells prior to filtration may reduce residual platelet levels to clinically acceptable numbers. The potential problem of antigenic leucocyte fragments may be decreased if fresh blood is used for filtration. A true assessment of the white cell antigenicity of filtered blood can only be obtained by clinical trials in sensitized patients.