ANTICARDIOLIPIN ANTIBODIES IN PATIENTS WITH PREGNANCY LOSS INDUCE FACTOR XA PRODUCTION IN THE PRESENCE OF BETA-2-GLYCOPROTEIN-I

PROBLEM: Anticardiolipin antibodies (aCL) are commonly associated with recurrent pregnancy loss, though the mechanism is uncertain. Some investigators have indicated that aCL may be directed at a complex made up of cardiolipin and a blood anticoagulant, beta 2-glycoprotein I (beta 2GPI). We therefore investigated the effects of beta 2GPI-dependent aCL IgG enriched fractions, isolated from sera of patients with pregnancy losses, on blood coagulation. METHOD: beta 2GPI-dependent aCL were prepared from sera of three women with second trimester pregnancy losses, by cardiolipin affinity column chromography, following by anti-beta 2GPI affinity column chromatography. The effects of beta 2GPI and beta 2GPI-dependent aCL on the activation of factor X in vitro were examined. RESULTS: beta 2GP1 inhibited the activation of factor X and beta 2GPI-dependent aCL blocked this inhibitory effect in a dose dependent manner. CONCLUSION: These results imply the possibility of beta 2GPI-dependent aCL induce hypercoagulation or thrombus by blocking the inhibitory effect of beta 2GPI on activation of factor X, which may result in pregnancy loss.