Factors affecting white cell content in platelet concentrates.

In this study, we investigated the factors affecting white cell content in platelet concentrates. White cell yields can be reduced 50 percent by stopping platelet-rich plasma expression when the interface is 1 cm from the top of the blood bag as compared to stopping expression when the interface reaches the top of the bag. Further reductions can be achieved by careful handling during transfer of units from the centrifuge cups to expressors (after the first spin) and by carefully balancing units against each other to ensure proper rotor balance during the first spin. Following these suggestions, blood banks should be able to produce platelet concentrates with white cell yields between 2 and 6 X 10(7) and with platelet yields between 7.5 and 8 X 10(10). Transfusion of this product may reduce febrile reactions and lower the incidence of alloimmunizations.