mAb CCR5–02 does not promote CCR5 down-regulation from the surface of stably transfected HEK-293 cells. (A) Serum-starved, CCR5-transfected HEK-293 cells were incubated as indicated with RANTES (10 nM), CCR5–02 mAbs (10 μg/ml), or isotype-matched control mAbs (10 μg/ml) at 37°C. Surface CCR5 was detected by FACS analysis using biotin-labeled CCR5–03 mAbs, followed by streptavidin-phycoerythrin; an isotype-matched mAb was used as a staining control. Results are expressed as the percentage of maximum binding in the absence of chemokine, with SD indicated. (B) A representative flow cytometry figure is shown for data from A, corresponding to RANTES or CCR5–02 mAb treatment (15 min, 37°C).