Patient-derived antibodies (and monoclonal antibody 4F3) do not recognize plasma-purified β2-GPI coated onto a hydrophobic plate. Plasma-purified β2-GPI and recombinant β2-GPI were coated onto hydrophilic (▪) and hydrophobic (▴) plates. Then, the plates were incubated with either patient plasma (A), patient IgG antibodies (B), monoclonal antibody 4F3, monoclonal antibody 2B2, or monoclonal antibody 27G7 (C). The bound mAbs were detected by a rabbit anti-mouse peroxidase-labeled antibody, and coloring was performed by OPD. To detect the bound patient IgG antibodies, the plates were incubated with an alkaline-phosphatase-labeled goat anti-human IgG antibody. PnPP was used as coloring substance. The obtained optical density (OD) was corrected for the optical density obtained with total IgG isolated from pooled plasma from 40 healthy volunteers (panel A hydrophilic plate: OD, 0.087; hydrophobic plate: OD, 0.130). Error bars represent mean ± SEM of duplicate points. Ab indicates antibody.
