[Comparative evaluation of 3 leukocyte filters for thrombocyte concentrates]

Several polyester adsorption filters are available for the removal of leukocytes during bedside filtration of platelet concentrates (PC). We tried to evaluate the efficacy of three leukocyte filters: PL-100 (Pall, USA), Sepacell PL-5A and PL-10A (both Asahi, Japan) using single donor PCs. All filters were used according to the manufacturer's instructions. The main difference in handling is the recommendation of priming and rinsing the Asahi filters with saline. Platelet counts were performed by an automatic cell counter, leukocyte (WBC) counts using a modified chamber method. Biocompatibility was examined by assessing anaphylatoxin, PMN-elastase and LDH levels, platelet function by measuring induced aggregation, hypotonic shock response, beta-thromboglobulin levels and the mean platelet volume. According to the different initial WBC contamination, three groups of PCs were tested. Group I and II were processed one hour after apheresis. Group III (n = 30) was stored at 12 degrees C up to five days before filtration. Function and integrity of post-filtration platelets were not affected as compared to the prefiltration status and bioincompatibility could not be detected. Our results indicate that the WBC reduction capacity of the filters is related to the initial WBC contamination of the PC. Beyond an initial contamination of 10(9) WBC, none of the filters is capable of reducing the leukocyte count below 10(6) WBC/PC. All but PL-5A reduce the WBC reliably below 10(6)/PC as determined from PCs routinely prepared. The Asahi filters cause significantly less platelet loss apparently due to the suggested postfiltration rinsing. Storage of PC does not influence the WBC reduction capacity, however increases the platelet loss for the PL-100.