Subcellular distribution of the human CCR5 receptor. (A) FACS analyses showing human resting T lymphocytes from healthy donor or THP-1 monocytes were stained for surface (left panels) and total (after cell permeabilization, right panels) CCR5 (top panels) or CD4 (bottom panels), using 1/85a anti–human CCR5 antibody or OKT4 anti–human CD4, respectively, and analyzed by flow cytometry. Green and red histograms correspond to specific labeling for CCR5 and CD4, respectively. Gray histograms are the isotypic control for each antibody. (B) Human resting T lymphocytes, THP-1, and Jurkat cells (negative control) were stained for surface (nonpermeabilized, NP) and total (permeabilized, P) CCR5 or CD4, using 2D7 anti–human CCR5 or OKT4 anti–human CD4 antibodies. Images were obtained by confocal microscopy. Scale bar, 10 μM. (C) THP-1 cells, expressing endogenous receptor, were stained with the 2D7 anti–human CCR5 antibody and antibodies directed against Bip, an ER marker, or Giantin, a Golgi marker (see “Methods”), and analyzed by confocal microscopy. Colocalization of CCR5 (green) with Bip or Giantin (both in red) is shown in orange (merge). Scale bar, 10 μM.