Analysis of the binding of monoclonal antibodies 12F1 and 6F1 to ADP-stimulated platelets. Unstimulated: PRP was incubated with each of the monoclonal antibodies 12F1 (left), 6F1 (middle), or P1E6 (right) and examined by flow cytometry (dashed lines). ADP stimulated: PRP containing each of the antibodies and ADP (20 μM) is represented by the dotted lines. Mouse IgG was used as control and is represented by solid lines. ADP stimulation increases 12F1 binding by an average of 38%, based on mean fluorescence intensities. The data were obtained from 8 different donors. There was no difference of P1E6 binding between unstimulated and ADP-stimulated platelets.