Functional cell surface expression of wild-type and mutated CXCR4 receptors after stable transfection of the HEK/CD4.403 cell line.

(A) Cells were incubated with PBS alone (white histograms) or a solution of SDF-1 at 100 nM (light gray histograms), 200 nM (dark gray histograms), or 400 nM (black histograms) in PBS at 4°C. After incubation of the anti–SDF-1 antibody at 10 μg/mL, bound antibody was detected with a FITC-labeled antirabbit immunoglobulin. Data representative of 1 to 5 experiments are shown. (B) Cells expressing CD4.403 and wild-type or mutated CXCR4 molecules were infected by the HIV–R7-GFP33 for 4 days as described in “Materials and methods,” and GFP⁺ cells were analyzed by flow cytometry. The percentage of R7-GFP–infected cells expressing wild-type CXCR4 is defined as 100% and corresponds to the ratio of GFP⁺ cells expressing wild-type CXCR4 to GFP⁺ cells that do not express CXCR4. The histograms represent the percentage of infected cells. Data are expressed as means ± SDs of 4 different experiments.