AbstractThe effect of the prestorage removal of leukocytes from platelet concentrates (PC) on the cytokine levels during its storage was studied. Two methods for leukocyte removal were examined: filtration and preparation of the PC by the buffy coat method. Cytokine levels were measured at various storage times. Highly increased levels of tumor necrosis factor‐α (TNF‐α; 120±131 ng/l) and interleukin 6 (IL‐6; 988±494 ng/l) were found after a 5‐day storage in the control group, whereas no increased levels were found in filtered PC (TNF‐α 14±4 ng/1, IL‐6<4 ng/l) or in buffy coat PC (TNF‐α 8±2 ng/l, IL‐6<4 ng/l). Furthermore an effect of the pooling of buffy coats or PC on the cytokine levels was not found. Transfusion of PC containing high levels of IL‐6 and TNF‐α has been associated with febrile transfusion reactions in the recipient and therefore the prestorage leukocyte removal might prevent these febrile transfusion reactions. The preparation of buffy coat PC, through its simplicity, seem