Anticardiolipin and anti-β2GPI antibodies in a large series of European patients with systemic lupus erythematosus

Objective. To test the prevalences and the clinical associations of anticardiolipin (aCL) and anti-β2GPI (aβ2GPI) antibodies in a large series of European patients with systemic lupus erythematosus (SLE). Methods. 574 SLE patients from 7 European countries were tested for aCL and aβ2GPI by ELISA methods. Results. aCL of IgG, IgM, and IgA isotypes were detected in 22.8%, 14%, and 13.9% of the patients, respectively. IgG and IgM aβ2GPI were detected in 20% of the patients. The presence of aCL was highly associated with the presence of aβ2GPI. Medium-high titer IgG aCL and aβ2GPI were associated with thrombosis, with similar sensitivity, specificity, and positive predictive value. When present at mediumhigh titer, IgG aCL were associated with thrombocytopenia, IgM aCL with hemolytic anemia, and cerebrovascular accidents, IgA aCL with livedo reticularis and Raynaud's phenomenon. Conclusion. aCL, when present at medium-high titer, are as important as ab2GPI, as a risk factor for thrombosis. Medium-high titer a...