The Clinical Performance of a New Chemiluminescent Immunoassay in Measuring Anti-β2 Glycoprotein 1 and Anti-Cardiolipin Antibodies

BACKGROUND Laboratory criterion is needed for the classification of antiphospholipid syndrome (APS), which contain anticardiolipin antibodies (aCL) and anti-β2-glycoprotein 1 antibodies (aβ2GP1). They are commonly identified by enzyme-linked immunosorbent assay (ELISA), but lack standardized kits, resulting in substantial variations in the antibody positivity between different laboratories. The emergence of chemiluminescence automated -BIO-FLASH may improve the situation. MATERIAL AND METHODS We selected 185 patients with APS, systemic lupus erythematosus (SLE), infertility, connective tissue disease (CTD), and other conditions in Peking University Third Hospital. We tested the aCL and aβ2GP1 levels by EUROIMMUN ELISA and 105 patients had at least one positive result for aCL and aβ2GP1, while the others had negative results. We retested them by chemiluminescence assay (CIA) and analyzed the result and compared the coincidence rate. The IgM levels were retested by AESKU ELISA. Data were analyzed using SPSS. RESULTS Our result suggested that CIA had good performance for IgG isotype of aCL and aβ2GP1 in the coincidence rate. The positive coincidence rate of aCL IgM between CIA and EUROIMMUN ELISA was only 41.67%, but two ELISA kits showed good coincidence, CIA and AESKU ELISA had an obviously higher positive rate. CIA and AESKU had a higher coincidence than that of AESKU and EUROIMMUN in aβ2GP1-IgM. CONCLUSIONS The new automated CIA BIO-FLASH is suitable for detecting aCL and aβ2GP1 antibodies, especially IgG isotype, which may provide an alternative to time-consuming conventional ELISA method.