EFFECTS OF WHITE CELL-REDUCTION ON THE RESISTANCE OF BLOOD COMPONENTSTO BACTERIAL MULTIPLICATION

Background: While prestorage white cell (WBC) reduction by filtration may improve platelet and red cell quality it also may remove an import ant anti-bacterial defense mechanism, especially if blood is WBC-reduc ed shortly after collection. Study Design and Methods: The question of whether WBC reduction of platelet concentrates and red cells altered bacterial proliferation kinetics in components prepared from deliberat ely contaminated, freshly collected blood was investigated. Two-unit p ools of whole blood were inoculated, at a concentration of approximate ly one colony-forming unit per mt, with one of 17 bacterial species re ported to have caused septicemia in transfusion recipients. Each pool was divided after inoculation, and components were prepared from the 2 units after a 7-hour room-temperature holding, period. One unit of ea ch AS-1 red cell or platelet pair was WBC-reduced, and pairs were then stored for 42 days at 4 degrees C (red cells) or for 10 days at 22 de grees C (platelets). Quantitative bacterial cultures were performed at periodic intervals. Results: In red cells. clinically significant bac terial proliferation occurred in only one instance (Serratia marcescen s), and growth was less rapid in the WBC-reduced unit than in the cont rol Three patterns of growth were seen in platelet concentrates. In fo ur cases, there was rapid proliferation in both test and control units , while on 13 occasions there was minimal replication in either pair. On six occasions, substantial growth was noted in control units, while few or no bacteria could be found in the WBC-reduced units. There was no evidence in either red cells or platelets that bacteria proliferat ed more rapidly in units that had been WBC-reduced before storage they did in units in which WBCs were retained. Conclusion: Rather than inc reasing the risk of bacterial proliferation through removal of active phagocytic cells, WBC reduction by filtration before blood storage may act to reduce the likelihood of significant bacterial proliferation, possibly by removal of microorganisms along with WBCs.