Dot blot analysis of two representative serum samples from patients having antibodies (IgG) to human prothrombin (II) before and after inhibition experiments. A, Serum diluted in buffer; B, phosphatidylserine (PS)/phosphatidylcholine (PC)-liposomal supernatant; C, PS/PC-liposomal eluant; D, fluid-phase inhibition with 200 μg/ml of II; E, fluid-phase inhibition with 100 μg/ml of II. Strips were dotted with 3 μg of II or bovine serum albumin (BSA). A normal serum is shown as control.