WHITE CELL-REDUCTION IN PLATELET CONCENTRATES AND PACKED RED-CELLS BYFILTRATION - A MULTICENTER CLINICAL-TRIAL

Background: Most previous studies on white cell (WBC) reduction by fil tration have been small-scale studies conducted under tightly controll ed laboratory conditions. Their results would be the ideal, rather tha n what might be expected during routine operation. Study Design and Me thods: To obtain information on routine filtration of blood components , data have been collected from a large-scale ongoing, multicenter cli nical trial designed to determine the effectiveness of WBC reduction i n or ultraviolet B radiation of platelet concentrates before transfusi on in preventing platelet alloimmunization and platelet transfusion re fractoriness. The WBC content of blood components both before and afte r filtration was determined by automated cell counters and a manual pr opidium iodide-staining method, respectively, Platelet and red cell lo sses during filtration were measured. Results: The average platelet lo sses after filtration were 24 +/- 15 percent and 20 +/- 9 percent for apheresis platelets and pooled platelets, respectively The frequencies at which filtered platelet concentrates contained high levels of resi dual WBCs (>5 x 10(6)) were 7 percent and 5 percent for apheresis plat elets and pooled Platelets, respectively. Further analysis of the plat elet filtration data showed that greater numbers of total initial WBCs in the pooled platelets were associated with increased percentages of filtration failure (>5 x 10(6) residual WBCs). For packed red cells, the average losses during filtration were 23 +/- 4 percent and 15 +/- 3 percent for CPDA-1 units and Adsol units, respectively. The frequenc ies at which filtered red cells contained >5 x 10(6) residual WBCs wer e 2.7 percent for one type of filter and 0.3 percent for another type of filter. Conclusion: There were significant losses of platelets duri ng filtration, which could add to the costs. of WBC reduction and lead to possible increases in donor exposures. Filtration failures still o ccurred, despite careful observation of the Standard filtration proced ures. The number of total WBCs in pooled platelets before filtration h as been identified as an important factor in determining the success o f WBC reduction.