Assessment of antiphospholipid antibodies using enzyme-linked immunosorbent assay and chemiluminescent method

Antiphospholipid antibodies (aPL) are a sign of acquired thrombophilia and are associated with recurrent thrombosis and obstetric pathology. According 2006 classification criteria, serological markers of antiphospholipid syndrome (APS) include lupus anticoagulant, moderate and high levels of antibodies to cardiolipin (aСL) and â2-glycoprotein 1 (anti- â2-GP1) IgG and IgM. The task of standardizing aPL values remains unresolved, leading to variability in results. Objective: to evaluate the comparability of IgG/IgM aCL and IgG/IgM anti- â2-GP1 measurement results using enzyme-linked immunosorbent assay (ELISA) and chemiluminescence (CLU) tests. Material and methods. Peripheral blood from 192 patients (147 women and 45 men) was analyzed, 55 patients (29%) had primary APS, 12 (6%) had probable APS, 61 (32%) had systemic lupus erythematosus (SLE) and APS, and 64 (33%) had SLE without APS. IgG/IgM aCL and IgG/IgM anti- â2-GP1 were determined in all participants by ELISA. By CLU method IgG/IgM aCL were analyzed in 192 patients and IgG/IgM anti- â2-GP1 in 191 patients. Results and discussion. The evaluation of the comparability of the results of ELISA and CLU revealed considerable discrepancies in the positive tests. Thus, in 16% of cases, a discrepancy was found in the levels of IgG aCL and IgM aCL by both methods (n=30 and n=31, respectively), in 18% in the level of IgG anti- â2-GP1 (n=34) and in 15% in the level of IgM anti- â2-GP1 (n=28).These discrepancies were to a greater extent associated with a more frequent detection of aPL in CLU when their values were negative in ELISA , indicating the greater information capacity of the CLU method. However, a small number of patients were positive for aPL in ELISA but negative in CLU: 5 with IgG aCL, 4 with IgM aCL, 6 with IgG anti-â2-GP1, and 2 with IgM anti- â2-GP1 . Conclusion. CLU is shown to be a more informative method for determining IgG aCL and IgG anti- â2-GP1 than ELISA (p<0.05).