Drug-dependent reactions of monoclonal 314.1 with intact platelets were similar to those of 2 human quinine-dependent antibodies. All studies were done with flow cytometry. (A) Reactions of mAb 314.1 (0.2, 1, and 5 μg/mL) at various concentrations of quinine. (B) Reactions of 2 human quinine-dependent antibodies at various concentrations of quinine. (C,D) Reactions of mAb 314.1 (1.0 μg/mL; C) and 2 human quinine-dependent antibodies (D) at various concentrations of quinine and quinine congeners. Drug concentrations are shown on the abscissa. Reactions of mAb 314.3 (not shown) were essentially identical to those of mAb 314.1.