Inhibition of the binding of anti-CCR5 mAbs by AK530, AK317, and APL. Inhibition by three CCR5 inhibitors of the binding of anti-CCR5 mAbs [45531 (a), 45523 (b), 2D7 (c), and 45549 (d)], which recognize the extracellular domain(s) of CCR5, is illustrated. CCR5-overexpressing CHO cells were incubated with each of FITC-conjugated anti-CCR5 mAbs in the presence of various concentrations of a CCR5 inhibitor and the fluorescence intensity on the cells was determined. Each value was compared to that obtained without an inhibitor and is shown as % control.