Recognition of recombinant β2-GPI and (deglycosylated) plasma-purified β2-GPI in solution. Type A IgG antibodies of patient 1 and patient 2 (B), monoclonal antibodies 4F3 (3 μg/mL) (C), F(ab) fragments of monoclonal antibody 4F3 (15 μg/mL) (D), and monoclonal antibody 2B2 (3 μg/mL) (D) were coated onto hydrophobic ELISA plates. Then, the plates were incubated with different concentrations of either plasma-purified β2-GPI, deglycosylated plasma-purified β2-GPI (A), or recombinant β2-GPI. Subsequently, the plates were washed and the bound β2-GPI was detected by a polyclonal goat anti-human anti-β2-GPI antibody. After washing, the plates were incubated with a rabbit anti-goat peroxidase-labeled antibody. Coloring was performed with OPD. The obtained optical density was corrected for the optical density obtained with total IgG isolated from pooled plasma from 40 healthy volunteers (panel B: OD, 0.179; panel D: OD, 0.117). Error bars represent mean ± SEM of quadruplicate points.
