Heterogeneity of platelet responsiveness to anti-CD36 in plasma associated with adverse transfusion reactions.

BACKGROUND AND OBJECTIVES: Antibodies to CD36 (anti-CD36) are clinically important. As some platelet immunoglobulins produced by transfusion or pregnancy have been shown to induce platelet activation and to play roles in non-haemolytic transfusion reactions (NHTRs), we investigated the in vitro response of platelets to plasma containing anti-CD36. MATERIALS AND METHODS: Plasma containing anti-CD36, implicated in the development of NHTRs and subsequent thrombocytopenia, was incubated with CD36-positive platelets. Plasma-induced platelet activation was examined by evaluating platelet aggregation and RANTES (regulated on activation, normal, T-cell expressed, and presumably secreted) release. RESULTS: Platelet activation was induced by plasma alone in four out of 20 CD36-positive subjects. In seven subjects, platelet activation was synergistically induced by the combination of epinephrine priming and the plasma. The platelets of the nine remaining subjects failed to respond to the plasma. Platelet activation induced by either the plasma alone or by synergy with epinephrine required the involvement of Fc gamma RIIa. The different responsiveness of the platelets was partially associated with the surface levels of CD36 and Fc gamma RIIa, but not with Fc gamma RIIa polymorphisms. CONCLUSIONS: Plasma containing anti-CD36, implicated in the development of NHTRs, exhibited a platelet-activating capability. Additionally, platelets from healthy human subjects exhibited a considerable degree of heterogeneity in their responsiveness to this plasma. The heterogeneity of these responses may determine the occurrence of anti-CD36-related NHTRs.