Thrombocytopenia in SLE and related autoimmune disorders: association with anticardiolipin antibody

Abstract

Anticardiolipin antibody levels were determined in 116 patients with systemic lupus erythematosus and related autoimmune disorders. Forty-three of these patients had a history of thrombocytopenia—36 of whom had SLE, three primary Sjögren's syndrome, two rheumatoid arthritis and two mixed connective tissue disease. IgG anticardiolipin antibody levels were raised in 31 (72%) of the 43 patients and IgM anticardiolipin antibody levels were raised in 19 (44%). There was a strong statistical correlation between thrombocytopenia and raised anticardiolipin antibody levels of both the IgG (P < 0.001) and IgM (P < 0.01) immunoglobulin classes. Of the 20 patients with the highest IgG anticardiolipin antibody levels 16 had a history of thrombocytopenia. We suggest that anticardiolipin antibodies may play a direct role in mediating platelet destruction in autoimmune disorders.