ADSORPTION OF ANAPHYLATOXINS AND PLATELET-SPECIFIC PROTEINS BY FILTRATION OF PLATELET CONCENTRATES WITH A POLYESTER LEUKOCYTE REDUCTION FILTER

Anaphylatoxins generated during storage of platelet concentrates (PCs) may potentially have side effects on platelet transfusion. We evaluat ed the anaphylatoxin-scavenging abilities of white blood cell reductio n filters. Among the commercially available filters for PCs, one made with polyester fiber (PL50) dramatically adsorbed C3a and C4a anaphyla toxins to the respective mean level of 1,721-208 ng/ml and 1,240-141 n g/ml in 3-day-old PCs. C3a and C4a were measured as the native and des Arg form of each complement by radioimmunoassay. C3a and C4a anaphyla toxins in the supernatant plasma fraction from 3-day-old PC again decr eased from 1,136 to 114 ng/ml and from 1,086 to 65 ng/ml, respectively . The filter also adsorbed 85% of platelet factor 4 (PF4) and 31% of b eta-thromboglobulin (beta-TG), which had been released from platelets into the plasma during storage. The plasma levels of adhesive proteins such as fibronectin, fibrinogen, and von Willebrand factor, and plasm a lactate dehydrogenase activity did not decrease after filtration. An other polyester filter (PL5A), on the other hand, significantly increa sed C3a and C4a levels with filtration. In addition, there was no PF4 adsorption ability during the filtration. The filters for red cells (R C50, BPF4, and R500A) had no anaphylatoxin adsorption capabilities. Th e observed specific adsorption of anaphylatoxins might be attributed t o the electrostatic force between the positively charged anaphylatoxin s with high pi and the possibly negatively charged filter membranes. S ince PF4 and beta-TG have positively charged moieties in the C-termina l position, the same adsorption mechanism might operate. We have obtai ned a useful scavenging filter for the evaluation of side effects of a naphylatoxins on patients who received old PCs.