ANTIBODIES TO PHOSPHOLIPIDS AND TO BETA(2 )GLYCOPROTEIN-I

Recent studies have shown that beta(2) glycoprotein 1 (beta(2)GPI), a plasma inhibitor of coagulation with affinity for anionic phospholipid s, is frequentlyy required for the formation of the epitopes recognize d by some anti-phospholipid antibodies. Six murine monoclonal antibodi es directed against human beta(2)GPI were compared with anti-beta(2)GP I antibodies associated with systemic lupus erythematosus and primary anti-phospholipid syndrome. The beta(2)GPI-dependent binding propertie s to neutral and anionic phospholipids were studied, as well as the ta rget epitopes on the beta(2)GPI molecule and the effect of various bet a(2)GPI treatments to get rid of contaminating phospholipids or to blo ck the beta(2)GPI-phospholipid interaction. The results are in favour of a direct binding of patient's antibodies to beta(2)GPI, in the abse nce of phospholipids. Anti-beta(2)GPI monoclonal antibodies, two of wh ich inhibited beta(2)GPI recognition by the antibodies from patients, possessed lupus-like anticoagulant propertie, thereby constituting an interesting model for a subset (beta(2)GPI-dependent) of anti-phosphol ipid antibodies.