Flow cytometric measurement of DDAbs in chimpanzee A-264, control chimpanzee, rhesus monkey 94-R021, and control rhesus monkey plasma alternatively using rhesus 94-R021 and human platelets in the presence or absence of 1 μmol/L of B or A2-L. Data represent the mean ± SD from three measurements. Binding of DDAbs is plotted as a relative fluorescence of FITC-labeled secondary antibody.