The flow rate significantly influences the leukocyte depletion rate duringprestorage in-line filtration of platelet concentrates

Background: White cell reduction of blood products minimizes the risks of a lloimmunization against HLA-antigens, the transmission of viral diseases an d the incidence of platelet transfusion reactions. One modern strategy is l eukocyte depletion with an integrated filter system immediately after prepa ration and prior to storage. Study design and methods: We evaluated the efficiency of a never in-line fi lter system Sepacell(R) PLX-5 BPS for leukocyte reduction of platelet conce ntrates (PC) from pooled huffy-coats. A total of 44 PCs were investigated w ith regard to different filtration flow rates (25-110 ml/min) and leukocyte depletion and thrombocyte recovery rates were analysed. Furthermore, we st udied the influence of filtration on PCs over a storage period of 6 days (n = 12) by investigation of pH, lactate and glucose. Platelet function was d etermined by means of hypotonic shock response, external shape change and e xpression of CD62p. Results: The mean leukocyte depletion rate was >log 5. After filtration the mean leukocyte count was 0.12 +/- 0.21 x 10(6). In 60% of the PCs the leuk ocyte count lay below the detection level of the Nageotte chamber, which is <0.3 x 10(5). The flow rate correlates significantly with the leukocyte co unt in the PCs (r = 0.325; p = 0.033) and therefore with the leukocyte depl etion rate (r = -0.422; p = 0.01). Flow rates under 40 ml lead to a signifi cantly lower leukocyte contamination. Only in one PC, at a flow rate of 84 ml/min, was the leukocyte threshold of 1 x 10(6) exceeded. We did not find a significant correlation between filtration flow rate and thrombocyte reco very (r = 0.315; p = 0.069). The mean platelet count in the PC was 2.88 +/- 0.47 x 10(11). Compared with the thrombocyte count in the pooled buffy coa t, the recovery was 68.6%. We observed a decrease of pH, glucose, external shape change and hypotonic shock response over the storage period while lac tate and the expression of CD62p increased. Conclusion: The filter system Sepacell(R) PLX-5 BPS proved to be suitable f or in-line filtration of platelet concentrates prior to storage. Filtration flow rates of up to 40 ml/min allowed efficient leukocyte depletion withou t significant loss in the quality of the platelet concentrates and the plat elet function in vitro. (C) 1999 Elsevier Science Ltd. All rights reserved.