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 inv estigators have indicated that aCL may be directed at a complex made u p of cardiolipin and a blood anticoagulant, beta 2-glycoprotein I (bet a 2GPI). We therefore investigated the effects of beta 2GPI-dependent aCL IgG enriched fractions, isolated from sera of patients with pregna ncy losses, on blood coagulation. METHOD: beta 2GPI-dependent aCL were prepared from sera of three women with second trimester pregnancy los ses, by cardiolipin affinity column chromography, following by anti-be ta 2GPI affinity column chromatography. The effects of beta 2GPI and b eta 2GPI-dependent aCL on the activation of factor X in vitro were exa mined. RESULTS: beta 2GP1 inhibited the activation of factor X and bet a 2GPI-dependent aCL blocked this inhibitory effect in a dose dependen t manner. CONCLUSION: These results imply the possibility of beta 2GPI -dependent aCL induce hypercoagulation or thrombus by blocking the inh ibitory effect of beta 2GPI on activation of factor X, which may resul t in pregnancy loss.