WHITE CELLS IN FRESH-FROZEN PLASMA - EVALUATION OF A NEW WHITE CELL-REDUCTION FILTER

BACKGROUND: Fresh-frozen plasma (FFP) has generally been regarded as a n acellular component. Recently, viable lymphocytes have been detected in this component and the question of irradiation of FFP for certain patients has been raised. Whether the numbers of white cells (WBCs) in FFP are sufficient to require WBC-reduction of acellular components f or patients receiving WBC-reduced cellular components has not been det ermined. WBC numbers in FFP were examined, and the performance of a ne w commercial WBC-reduction filter far FFP was assessed. STUDY DESIGN A ND METHODS: WBC numbers in plasma processed for use as FFP and in thaw ed FFP were counted before and after WBC-reduction filtration by the u se of flow cytometry. Fast and slow filtration was used to simulate la boratory and bedside filtration, respectively. Three different methods far plasma harvesting (soft-spin, hard-spin, and second-spin methods) were assessed.The filter capacity was also examined. RESULTS: The num bers of WBCs in plasma covered a three-log,, range (soft-spin method, 0.04-3.6 x 10(6); hard-spin method, 0.47-45.4 x 10(6); second-spin met hod, 0.4-37.2 x 10(6)). For the hard-spin and second-spin methods whic h produced the greatest plasma yields, 92 percent and 85.7 percent of bags, respectively, had counts >1 x 10(6) and 43 percent (hard-spin me thod) and 45.7 percent (second-spin method) had counts >5 x 10(6). The re was no significant difference between the counts obtained in plasma and thawed FFP. The filter reduced WBC numbers to <1 x 10(5) in all b ut 3 of 49 bags. In the remaining three, there were <2 x 10(5) WBCs. F ive bags of plasma could be processed effectively through each filter. CONCLUSION: FFP may contain WBC numbers above the threshold at which the use of WBC-reduction filters for cellular components in some patie nts is necessary. Confirmation of these findings and similar investiga tions on plasma prepared by other methods may help in defining a role for the use of WBC-reduction filters for FFP.