FIG. 2.

MAbs 17b, 48d, and CG10 bind to HIV envelope-expressing cells in the presence of sCD4. Env cells were either untreated or incubated with 1 μg of sCD4/ml in DMEM for 120 min at 4°C and then either fixed with BS³ or directly stained with the indicated MAbs (visible in red) as described in Materials and Methods. MAbs were tested in parallel, along with human isotype controls, which produced no binding signal (data not shown). Representative images are shown. Each experiment was repeated at least three times with the same results. Scale bar, 10 μm.