NEW TARGETS OF [[ANTIPHOSPHOLIPID]] ANTIB ODIES

<<Antiphospholipid>> antibodies (aPL) are a heterogenous group of auto antibodies with clinical importance because of their association with thrombotic events, both venous and arterial. Traditionally, aPL have b een assayed using phospholipid-dependent tests and are classified as l upus anticoagulants and anticardiolipin antibodies (ACA), based on the method of detection. Most antibodies associated with the aPL syndrome and detected in standard assays are actually directed against two pho spholipid-binding plasma proteins, beta(2)-glycoprotein I and prothrom bin. These antibodies can also be detected in immunoassays (ELISA) uti lizing purified protein antigens, in the absence of phospholipids. The main advantage of beta(2)GPI-ELISA compared with conventional cardiol ipin-ELISA appearing from initial clinical studies is greater specific ity for the aPL syndrome, due to (i) ignorance of <<authentic>> ACA th at interact directly with cardiolipin; (ii) detection of species speci fic anti-beta(2)GPI antibodies poorly reactive with bovine beta(2)GPI in the cardiolipin-ELISA. Other proteins proposed as target antigens o f aPL are protein C, protein S, annexin V, high- and low-molecular wei ght kininogens, the latter being involved in the binding of antibodies to phosphatidylethanolamine. The possibility that particular autoanti bodies (or combinations of autoantibodies) explain the observed clinic al spectrum of the aPL syndrome is attractive, but much remains to be learned about their pathogenicity and origin in order to improve diagn osis and therapy.