Figure 2.

CCR5 activation by the multidomain mAb MC-6. Effect of different concentrations of RANTES (A) and anti-CCR5 mAbs at 10 μg/ml (B) on the binding of [³⁵S]GTPγS to membranes of CHO-K1 cells expressing human CCR5. Data are presented as raw cpm values (A) or normalized (B) to basal (0%) and maximal [³⁵S]GTPγS binding in response to RANTES (100%). These experiments were repeated four times with similar results. All data points were analyzed in triplicates (error bars: SEM). (C) Inhibition of forskolin-stimulated cAMP accumulation. CHO-K1 cells expressing CCR5 were incubated for 20 min with 5 μM forskolin and RANTES or the various mAbs, and cAMP was measured by enzyme-linked immunosorbent assay. The results were normalized for basal (0%, in the presence of forskolin only) and maximal response (100%, cAMP levels obtained with a saturating concentration of RANTES). The experiments were performed in triplicate (error bars: SEM), and the figure represents a typical experiment out of two performed independently.