Figure 4. Cells co-expressing CD4 and HIV-1 gp140 Envelope protein reduce over time during the NK cell activation ADCC assay. (A) HIV-1 gp140 envelope protein antigen stimulation of the whole blood samples in the NK cell activation ADCC assay in the presence of HIV⁺ plasma induces NK cell IFNγ expression. (B) Cells co-expressing CD4 and gp140 reduced in number over time (% baseline) in the presence of HIV positive serum (right graph) but not in the presence of HIV negative serum (left graph). (C) The reduction in the number of cells co-expressing CD4⁺ and gp140 was associated with an increase in Annexin V expression over time in the same population when incubated in the presence of HIV+ plasma (white bars) compared with HIV- plasma (black bars).