AUTOANTIBODIES TO HUMAN PROTHROMBIN AND CLINICAL MANIFESTATIONS IN 207 PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS

Objective. Prothrombin (factor II) is one of the phospholipid binding proteins with a procoagulant property. Some publications have shown th e presence of autoantibodies against prothrombin (aPT) in patients wit h antiphospholipid antibodies (aPL). We assessed the clinical signific ance of aPT in thrombotic events in patients with systemic lupus eryth ematosus (SLE). Methods. IgG and IgM aPT were tested by ELISA in 207 p atients with SLE, Results. Fifty-eight patients (28%) had positive aPT (> mean + 3 SD of 100 controls). Twenty-eight (14%) had IgG alone, 21 (10%) IgM alone, and 9 (4%) had both IgG and IgM, Patients with aPT h ad a history of thrombosis more frequently than those without aPT [31/ 58 (53%) vs 47/149 (32%), chi-squared = 7.6, p = 0.006]. No correlatio n was found between the presence of aPT and clinical features of SLE. Conclusion. aPT are frequently found in patients with SLE, and are a p otential marker for thrombosis.