Anti-platelet antibodies in sera from patients with systemic lupus erythematosus by immunoblot analysis

: It has not been clarified that the anti-platelet antibodies are related to thrombocytopenia in systemic lupus erythematosus (SLE). We evaluated the presence of anti-platelet antibodies in sera from patients with SLE using immunoblot analysis. In this study, 19 of 65 cases (29.2%) in SLE had anti-platelet antibodies in their sera, whereas no anti-platelet antibodies were detected in 16 cases of rheumatoid arthritis, 16 cases of progressive systemic sclerosis, 2 cases of polymyositis-dermatomyositis and 10 healthy controls. Six bands of 200 kDa, 140 kDa, 120 kDa, 95 kDa, 80 kDa and 65 kDa molecular weight were detected using immunoblot analysis. The platelet antibodies to 95 kDa and 80 kDa proteins were frequently detected in 12.3% and 16.9% respectively of SLE. These 2 antibodies were absorbed with the platelet pellet derived from healthy person. Therefore, it was suggested that the antibodies to 90 kDa and 80 kDa platelet antigens were specific to platelet membrane protein. Although we could not find any correlation between clinical and laboratory manifestations of SLE and these platelet antibodies, these antiplatelet antibodies were specifically detected in sera from patients with SLE by immunoblot analysis.