Results of inhibitor neutralization assays. The procedure is described in Materials and Methods. The plasmas were tested for neutralization by increasing concentrations of the A2 (-□-) or C2 (-⋄-) domains, by the LCh (-▵-), or by synthetic peptide 355-362 (○) and compared with an inhibitor control without the fVIII polypeptides (0% neutralization). Patient plasmas tested were hemophiliacs R7611 (1A), KB (1B), GK1831 (1C), and WD (1D).