Two cases of platelet transfusion refractoriness associated with anti‐CD36

BACKGROUND: Antibodies to platelet (PLT) glycoprotein (GP) IV (CD36) have been implicated in rare cases of PLT refractoriness, particularly in non-Caucasians. We report two cases of PLT transfusion refractoriness linked to anti-CD36. STUDY DESIGN AND METHODS: A 5-year-old female of Lebanese descent and a 70-year-old male of Chinese descent both failed to respond to HLA-matched PLT transfusions during acute myelogenous leukemia induction therapy. Antibody screening was performed using a PLT antibody solid-phase kit (PAKPLUS, GTI Diagnostics), followed by the monoclonal antibody-specific immobilization of PLT antigen (MAIPA) test and, for the second case, the modified antigen capture enzyme-linked immunosorbent assay (MACE). RESULTS: Both patients demonstrated antibody to GP IV (CD36) on the PAKPLUS assay. On MAIPA testing, both phenotyped as CD36 negative. Anti-CD36 was demonstrated by MAIPA in the first case. In the second case, antibodies were not detected by MAIPA and variably detectable by MACE, depending on the mouse monoclonal antibody (MoAb) used. Because no Canadian CD36-negative donors were available, antigen-negative plateletpheresis units from the BloodCenter of Wisconsin were successfully transfused. CONCLUSION: Two cases of clinically significant CD36 antibodies are reported. Investigation of one case was complicated by steric inhibition of binding in the MAIPA and MACE assays with certain MoAbs. The cases demonstrate the importance of maintaining an ethnically diverse pool of rare donors and the value of international cooperation in the management of these patients.