ANTIBODIES TO PROTHROMBIN IN ANTIPHOSPHOLIPID SYNDROME AND INFLAMMATORY DISORDERS

Antiphospholipid antibodies associated with the antiphospholipid syndr ome (APS) have been shown to bind plasma proteins, particularly beta 2 -glycoprotein I(beta 2-GPI), In this study the incidence of antibodies to solid-phase pro thrombin was examined in patients with antiphospho lipid syndrome and a variety of other inflammatory disorders. Signific antly elevated levels of IgG anti-prothrombin (anti-PT) antibodies wer e detected in 63% of patients with APS (n = 27, median 22 arbitrary un its: AU), 33% with SLE (n = 92, median 14 AU), 45% with rheumatoid fac tor (n = 22, median 16 AU), 21% with carotid artery stenosis (n = 21, median 15 AU), 32% with stroke (n = 38, median 13 AU), 67% of patients with a false positive serology for syphilis (n = 21, median 24 AU), 3 7% with HIV (n = 30, median 14 AU), 29% with syphilis (n = 14, median 19 AU) and 3% with infectious mononucleosis (n = 30, median 9 AU). In addition, a group of lupus anticoagulant (LA) positive patients (n = 4 8) was examined for antibodies to prothrombin, beta 2-GPI and cardioli pin. 10 (21%) patients had raised levels of IgG anti-PT antibodies, 30 (62%) had significantly elevated levels of anti-beta 2-GPI antibodies and 15 (31%) had elevated levels of anticardiolipin antibodies (ACA). Of the LA-positive patients, 15 (43%) were identified with definite A PS, eight (23%) with probable APS, two (6%) with possible APS and 10 ( 28%) patients had no clinical evidence of APS. In conclusion, antibodi es to prothrombin were found in a variety of inflammatory disorders an d were therefore not specific for the APS. However, identification of the plasma proteins recognized by antibodies from patients with APS ma y provide insight into the pathogenic mechanisms involved in the heter ogenous clinical manifestations of the APS.