Serum anti-beta(2)-glycoprotein-I and anticardiolipin antibodies during thrombosis in systemic lupus erythematosus patients

PURPOSE: Antibodies to beta(2)-glycoprotein-I are more strongly associated with clinical antiphospholipid syndrome than are anticardiolipin antibodies . We previously found a decrease in anticardiolipin antibodies at the time of thrombosis in 6 patients with systemic lupus erythematosus (SLE). We the refore sought to determine the prevalence and levels of antibodies to beta( 2)-glycoprotein-I and to cardiolipin before, during, and after thrombosis i n patients with SLE, and to compare them with patients who did not have thr ombosis. METHODS: We studied 24 patients with SLE who had at least one episode of th rombosis and 102 patients with SLE without thrombosis. Serum anticardiolipi n antibodies were measured by conventional enzyme-linked immunosorbent assa y (ELISA) using newborn calf serum as the blocking agent. Serum anti-beta(2 )-glycoprotein-I antibodies were measured by ELISA on nonirradiated plates, using purified human beta(2)-glycoprotein-I without phospholipid. RESULTS: All patients with thrombosis had anti-beta(2)-glycoprotein-I antib odies, compared with only 17% of controls (P <0.0001). We observed a signif icant decrease in serum anti-beta(2) glycoprotein-I levels at the time of t hrombosis, as compared with previous and subsequent samples. The prevalence and levels of IgG and IgM anticardiolipin antibodies were similar in patie nts with and without thrombosis. A decrease in IgG or IgM anticardiolipin t iters occurred during thrombosis in 6 patients. Anticoagulant, corticostero id, and immunosuppressive treatments did not appear to affect anti-beta(2)- glycoprotein-I levels at the time of thrombosis. CONCLUSION: Anti-beta(2)-glycoprotein-I antibodies are strongly associated with thrombosis in patients with SLE. The decrease of anti-beta(2)-glycopro tein-I levels at the time of thrombosis may indicate a pathogenic role. Thi s antibody may also be a marker of predisposition for thrombosis in these p atients. (C)1999 by Excerpta Medica, Inc.