Clinical significance of anti-phosphatidylserine-prothrombin complex antibodies in antiphospholipid syndrome

We clarified the clinical significance of IgG anti-phosphatidylserine-prothrombin complex (PS-PT) antibodies in the antiphospholipid syndrome (APS). The study population consisted of 122 patients with SLE and lupus-like disease. IgG anti-PS-PT antibodies were detected in 44% of 59 patients according to the diagnostic criteria by Harris and Hughes. This frequency was significantly (p < 0.005) higher than the 14% seen in patients without APS. IgG anti-PS-PT antibodies were strongly (p < 0.005) associated with thrombosis. In addition, IgG anti-PS-PT antibodies were positive in 64% of IgG beta2-GPI dependent anti-cardiolipin antibody negative APS patients under the Sapporo criteria. The above findings indicate that IgG anti-PS-PT antibodies as well as beta2,-GPI dependent anti-cardiolipin antibodies should be examined in the diagnosis of APS.