Heterogeneous behavior of anti-β₂-glycoprotein I antibodies on various commercially available enzyme immunoassay plates coated with β₂- glycoprotein I

Objective. To evaluate commercially available enzyme immunoassay (EIA) plates for the measurement of anti-β₂-glycoprotein I autoantibody (anti- β₂-GPI). Methods. Sera from 10 patients with the antiphospholipid syndrome, and 3 monoclonal anti-β₂-GPI antibodies established from patients with antiphospholipid syndrome, were assayed for binding to solid phase β₂-GPI on 20 commercially available plates. Results. Several commercially available EIA plates were found to be of potential value for the measurement of anti- β₂-GPI autoantibody. Some plates were unsuitable for anti-β₂-GPI detection, possibly due to less β₂-GPI on the plates, or to differences in the nature of conformational changes of β₂-GPI induced by the plates. Conclusion. Differences among EIA plates need to be considered when measuring β₂-GPI antibodies.