ANTIBODIES TO PHOSPHOLIPID-BINDING PLASMA-PROTEINS AND OCCURRENCE OF THROMBOSIS IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS

There is accumulating evidence that anti-phospholipid (aPL) antibodies in the sera of patients with autoimmune diseases bind to a complex of anionic phospholipids and plasma phospholipid-binding proteins, namel y beta 2-glycoprotein I (beta 2-GPI) and prothrombin. It has been sugg ested that a conformational change in beta 2-GPI, induced by binding e ither to anionic phospholipids or to the oxygen molecules on the irrad iated microtiter plate, reveals cryptic antigenic epitope(s) in the na tive protein. We used an enzyme-linked immuno-assay for measuring anti bodies against two phospholipid-binding proteins, i.e., beta 2-GPI and prothrombin, absorbed to an irradiated plate in an unselected series of 139 patients with systemic lupus erythematosus (SLE). Elevated leve ls of antibodies against beta 2-GPI were found in 49% of patients and antibodies against prothrombin in 34% of patients. Both antibodies wer e significantly associated with deep venous thrombosis in patients wit h SLE (P = 0.009 for both antibodies). Accordingly, testing of these a ntibodies seems to be clinically useful in evaluating the risk of thro mbosis. (C) 1996 Academic Press, Inc.