Figure 3

Enhanced downmodulation of CCR5 by preincubation of CCL5 with serum or CSA. A) CCL5 (1 μg/ml) was preincubated with various concentrations of human serum diluted in PBS and then used to downmodulate CCR5 from CCR5-transfected CHO cells. Low concentrations of serum significantly (p = 0.007) enhance the ability of CCL5 to downmodulate CCR5 from the surface of CHO cells. Serum alone did not induce downmodulation of CCR5 from the surface of CHO cells (data not shown). B) CCL5 (0.3 μg/ml) was preincubated with various concentrations of CSA and then used to downmodulate CCR5 from the surface of human monocytes. CSA alone did not affect CCR5 expression on monocytes (data not shown), but increased the CCL5-induced downmodulation of CCR5 significantly (p = 0.03).