Evaluation of new commercial enzyme-linked immunosorbent assay kits in the laboratory diagnosis of antiphospholipid syndrome in view of the revised classification criteria of the antiphospholipid syndrome.

Amendments to the Sapporo criteria for the diagnosis of the antiphospholipid syndrome (APS) have recently be published and include testing for the presence of IgG and IgM beta2-glycoprotein I (beta(2)GPI) antibodies. The Asserachrom Antiphospholipid antibodies line (Diagnostica Stago) with a monoclonal based standardisation, was evaluated in a Lupus anticoagulant (LAC) positive (n = 138) and a LAC negative (n = 134) populations. The ELISA line consists of the Asserachrom APA Screen, the Asserachrom APA IgG,M and the Asserachrom anti-beta(2)GPI IgG and IgM. Anti-prothrombin antibodies (APT), not being included in the updated laboratory criteria, have been tested by the Asserachrom anti-prothrombin IgG,M. Imprecision characteristics showed coefficients of variation (CV) ranging from 4.9% to 13.9%. Cut-off values were calculated with the 99 percentile. The Asserachrom APA Screen showed 1,5% false positive and 0,7% false negative results in correlation with the Asserachrom APA IgG,M. 14.7% of the patients were positive for beta2GPI antibodies, 30,0% of them showed a negative Asserachrom APA Screen. beta(2)GPI antibodies may be the only test positive in a minority of patients, so the Asserachrom APA Screen and the Asserachrom anti-beta(2)GPI IgG and IgM should be performed in parallel when APS is suspected. LAC and APA assays, however, remain essential in the laboratory diagnosis of APS.