Association between thrombosis and 2 different antibody populations. The association between the presence of a history of thrombosis and the ratio of ODs obtained with domain I coated onto hydrophobic or a hydrophilic ELISA plate, for type A and type B anti-β2GPI antibodies. Hydrophilic and hydrophobic ELISA plates were coated with 10 μg/mL domain I. Antibody binding was detected by an alkalic-phosphatase–labeled goat antihuman IgG antibody. The OD obtained with pooled plasma of 40 healthy volunteers was subtracted from the ODs obtained with patient plasma. As an estimation of the relative amount of antibodies reactive with the positive epitope on domain I, the OD obtained with the domain I ELISA on a hydrophobic plate was divided by the OD obtained with the domain I ELISA on a hydrophilic plate.
