Objective: To examine IgG anti-beta 2 glycoprotein I (anti-beta 2 GPI) binding in 82 sera referred for anticardiolipin antibody (aCL) testing and to develop preliminary clinical correlations with antiphospholipid syndrome (APS).
Methods: Immunoassay of IgG cofactor dependent aCL and IgG anti-beta 2 GPI antibodies and retrospective chart review.
Results: Forty-four sera exhibited normal (< or = 22 GPL units) aCL activity, 18 had moderate binding activity (23-45 GPL units), and 20 had high (> or = 46 GPL units) binding activity to cardiolipin. Among these groups, 6 of the 20 sera in the high GPL group had elevated anti-beta 2 GPI. This correlated strongly with 2 or more clinical manifestations of APS.
Conclusion: Anti-beta 2 GPI activity may be a more valuable indicator of APS than aCL.