Reactions to platelet transfusion: the effect of the storage time of the concentrate.

Random platelet concentrates were pooled and depleted of leucocytes by centrifugation immediately prior to transfusion. The incidence and severity of reactions to 570 leucocyte-poor platelet transfusions in 74 patients were studied. An overall transfusion reaction rate of 13.7% was observed. The reaction rate to platelets stored for less than 3 days (8.7%) was significantly different from the reaction rate to platelets stored for 3 days or more (17.6%). Minor reactions as well as moderate and severe reactions were more frequent in the latter group. As most of the white blood cells were removed prior to transfusion, it is suggested that the reactions result from the transfusion of pyrogenic and/or vasoactive substances accumulated in the plasma of the concentrate during storage.