To evaluate the diagnosis value of antibodies to phosphatidylserine/prothrombin complex (aPS/PT) in patients with antiphospholipid syndrome (APS) and to determine the clinical features of APS patients with avidity of aPS/PT. Serum samples were collected from 108 APS patients. Sixty patients with pregnancy morbidity, 37 patients with thrombosis without a history of autoimmune diseases, and 89 healthy blood donors were included as the control group. The enzyme-linked immunosorbent assay (ELISA) test was performed to detect the concentration of aPS/PT, including IgG/M, IgG, and IgM forms, in the same serum sample. The chi-square (χ2) test was used to examine the difference of frequencies of antibodies in APS patients and patients with other diseases. Spearman correlation analysis was performed to investigate the relationship between aPS/PT and other clinical/laboratory parameters. aPS/PT was detectable in 68 (63.0%) of the 108 APS patients, 12 (13.2%) of the 91 disease control patients and 1 (1.1%) of the healthy controls. It was strongly correlated with the activity of lupus anticoagulant (LA) (OR 15.952, 95% CI 7.132-35.678; P < 0.001). The frequency of aPS/PT was 56.9% in anti-cardiolipid antibody (aCL)-negative, 60.5% anti-β2 glycoprotein I antibody (aβ2GPI)-negative, and 50.0% in both aCL and aβ2GPI negative APS patients. The IgG aPS/PT was significantly associated with arterial and venous thrombosis. The aPS/PT antibody could play an important role in the diagnosis of APS, especially in patients with negative aCL and aβ2GPI. It was positively related to thrombotic events in APS.
Keywords: Antiphosphatidylserine/prothrombin antibodies; Antiphospholipid; Pregnancy morbidity; Sensitivity; Specificity; Syndrome·thrombosis.