The use of an anti-beta 2-glycoprotein-I assay for discrimination between anticardiolipin antibodies associated with infection and increased risk of thrombosis.

Antiphospholipid antibodies (aPAs), occurring in association with infection, are not generally associated with an increased risk of thrombosis. Anticardiolipin antibodies (aCL) from patients with infection, unlike those from patients with SLE, do not have the beta 2GPI cofactor requirements. Antibodies to beta 2GPI (alpha beta 2GPI) are more closely associated with a previous history of thrombosis than aCL in patients with SLE. In the present study we have investigated the reactivity of the alpha beta 2GPI assay for aPAs associated with infection. Serum from 114 patients with infections including syphilis (n = 11), tuberculosis (n = 63) and Klebsiella (n = 42) were assayed for alpha beta 2GPI and aCL antibodies. The incidence of aCL in serum of patients with tuberculosis. Klebsiella infection and syphilis was 6.0%, 5.0% and 64.0%, respectively, but all patients were negative for alpha beta 2GPI. These results indicate that the alpha beta 2GPI assay is negative in patients with transiently positive aCL assays associated with infection.