Isotypes of anti-beta(2)-glycoprotein I antibodies: Association with thrombosis in patients with systemic lupus erythematosus

Objective. To evaluate the association between isotypes of anti-beta (2)-gl ycoprotein I antibodies (anti-beta (2)-GPI) and thrombosis and to identify antiphospholipid antibodies (aPL) that are most associated with thrombosis in patients with systemic lupus erythematosus (SLE). Methods. IgG anticardiolipin antibody (aCL) and isotypes of anti-beta (2)-G PI were measured by ELISA, and clinical evidence of thrombosis was analyzed in 270 patients with SLE. Results. IgG, IgM, and IgA anti-beta (2)-GPI were positive in 38.1, 13.7, a nd 34.8% of patients, respectively. Patients with a history of thrombosis w ere significantly more likely to have lupus anticoagulant (LAC), IgG aCL, a nd the 3 anti-beta (2)-GPI isotypes. Arterial thrombosis was associated wit h the presence of IgG aCL and the 3 anti-beta (2)-GPI isotypes, whereas ven ous thrombosis was associated with LAG, IgG aCL, and IgA anti-beta (2)-GPI. In stepwise multivariate logistic regression analysis, the variable that w as associated with thrombosis was IgA anti-beta (2)-GPI. The occurrence of arterial thrombosis was associated with IgG aCL and that of venous thrombos is was related to IgA anti-beta (2)-GPI in stepwise multivariate analysis. The IgG, IgM, and IgA anti-beta (2)-GPI titers were closely correlated with Ige aCL titers. The IgA anti-beta (2)-GPI titers were also significantly c orrelated with those of IgG and IgM anti-beta (2)-GPI. Conclusion. The results suggest that anti-beta (2)-GPI isotypes are related to the occurrence of thrombosis, and measurements of IgA anti-beta (2)-GPI may be useful for predicting thrombotic episodes in patients with SLE.