ELLAGIC ACID PHOSPHOLIPID-INDUCED COAGULATION AND DEXTRAN SULFATE-INDUCED FIBRINOLYTIC-ACTIVITIES IN BETA(2)-GLYCOPROTEIN I-DEPLETED PLASMA

beta 2-glycoprotein I(beta 2-GPI) binds negatively charged substances and inhibits intrinsic blood coagulation in the presence of ellagic ac id-phospholipid suspension. beta 2-GPI is thought to be an important p rotein in the reaction between negatively charged phospholipids and an ti-phospholipid antibodies which appear in patients with lupus anticoa gulant/antiphospholipid antibody syndrome. We prepared a monoclonal an tibody against beta 2-GPI purified from human plasma and obtained beta 2-GPI-depleted plasma using a monoclonal antibody-coupled column. Eit her partial thromboplastin time or the activation of prekallikrein ind uced by diluted ellagic acid-phospholipid suspension in beta 2-GPI-dep leted plasma was not different from that in control plasma. beta 2-GPI inhibited the intrinsic blood coagulation only when added to control or beta 2-GPI-depleted plasma in excess (more than physiological conce ntrations). The. intrinsic fibrinolysis in beta 2-GPI-depleted plasma induced by dextran sulfate was not impaired and, again, beta 2-GPI inh ibited the intrinsic fibrinolysis only when added to control or beta 2 -GPI-depleted plasma in excess. These results indicate that both in vi tro Actin(R)-induced intrinsic coagulation and dextran sulfate-induced fibrinorytic activities are significantly inhibited by more than phys iological concentrations of beta 2-GPI.