FIG 6.

CD4-induced cluster A epitopes are important for HIV-1⁺ plasma antibody binding and ADCC against HIV-1_AD8-infected and uninfected CEM cells. (A) The graphs depict the binding of IgG within HIV-1⁺ plasma (1:1,000; n = 13) to CD4^hi GFP^– uninfected cells and to CD4^int GFP^lo and CD4^lo GFP^hi infected cells after preincubation with or without A32 Fab (10 μg/ml). The dotted black line depicts plasma IgG binding of an HIV-1-uninfected donor. Plasma IgG binding was determined using flow cytometry, and results are presented as MFI values. (B) ADCC mediated by HIV-1⁺ plasma antibodies (1:1,000) against HIV-1-infected CEM cells sorted into GFP^– (n = 11), GFP^lo (n = 10), and GFP^hi (n = 7) populations in the presence or absence of A32 Fab (10 μg/ml). Statistical analyses between matched pairs were performed with a Wilcoxon signed-rank test (ns, not significant; **, P < 0.01; ***, P < 0.001).