Inhibition of fVIII functional activity in coagulation assays. Equal volumes of BO2C11 and of a pool of normal plasma were incubated for 2 hours at 37°C. BO2C11 concentrations before mixing with plasma were as indicated. The residual fVIII activity was measured in an one-stage coagulation assay and was expressed as the percentage of the activity obtained in the absence of antibody.