HLA-C expression on platelets: Studies with an HLA-Cw1-specific human monoclonal antibody

Background and Objectives: The expression of HLA-C on the surface of platelets is rarely studied due to the lack of proper alloantisera, We addressed this question using an IgM human monoclonal antibody directed against HLA-Cw1 (VP6G3), Material and Methods: Both flow cytometry and complement dependent cytotoxicity studies were used in the current analysis, Results: The expression of the HLA-Cw1 antigen on platelets is lower than on peripheral blood lymphocytes as shown by flow cytometry, Variation in expression levels between individuals is also observed, Using this antibody in a complement dependent cytotoxicity assay, we did not observe lysis using platelets as targets, whereas peripheral blood lymphocytes of the same blood donors were adequately lysed, Conclusions: These results confirm that platelets indeed express HLA-C, Furthermore, the results support the insignificant role of HLA-C in immunological platelet refractoriness, Copyright (C) 2000 S. Karger AG, Basel.