The mAb were analyzed for their binding to β2GPI (panel A), thrombin (B), APC (C) and plasmin (D). Microtiter wells were coated with the indicated autoantigens, and the test mAb, or the monoclonal isotype controls (IgG1 or IgG3) were analyzed at 1 μg/ml. Except for B2 (which is IgG3), all mAb are IgG1. Bound IgG were measured and expressed in OD. One of two experiments with similar results is shown.