The role of the plasma from platelet concentrates in transfusion reactions.

Background: Febrile, nonhemolytic transfusion reactions are the most frequent adverse reactions to platelets. A number of observations argue against the widely held view that these reactions result from the interaction between antileukocyte antibodies in the recipient and leukocytes in the platelet product. We sought to determine whether substances in the plasma or the cells in the product cause reactions to transfused platelets.

Methods: We separated standard platelet concentrates into their plasma and cellular components and then transfused both portions in random order. Patients were monitored for reactions during all transfusions. Before each transfusion, the concentration of cytokines (interleukin-1 beta and interleukin-6) was measured in the platelet products. Studies were also performed on the platelet products to determine the effect of storage on the concentration of cytokines.

Results: Sixty-four pairs of platelet-product components (the plasma supernatant and the cells) were administered to 12 patients. There were 20 reactions to the plasma supernatant and 6 reactions to the cells (chi-square = 6.50, P = 0.009). Eight transfusions were associated with reactions to both products. The plasma component was more likely to cause severe reactions than the cells (chi-square = 9.6, P < 0.01). A strong positive correlation was observed between the reactions and the concentration of interleukin-1 beta and interleukin-6 in the plasma supernatant (P < 0.001 and P = 0.034, respectively). In vitro studies demonstrated that interleukin-1 beta and interleukin-6 concentrations rise progressively in stored platelets and that these concentrations are related to the leukocyte count in the platelet product.

Conclusions: Bioreactive substances in the plasma supernatant of the platelet product cause most febrile reactions associated with platelet transfusions. Removing the plasma supernatant before transfusion can minimize or prevent these reactions.