FIG. 4.

Gag-specific CD4⁺ T-cell responses in the chronic phase. PBMCs around week 30 postchallenge were stimulated with p55, and specific induction of IFN-γ, TNF-α, IL-2, MIP-1β, and CD107a in CD4⁺ T cells was examined. (A) Frequencies of total Gag-specific CD4⁺ T cells. (B) Percentages of cells exhibiting Gag-specific induction of single or multiple marker cytokines in total Gag-specific CD4⁺ T cells. See the legend to Fig. 2 for symbols. (C) Frequencies of polyfunctional Gag-specific CD4⁺ T cells exhibiting Gag-specific induction of ≥3 marker cytokines in total CD4⁺ T cells. The frequencies in NAb-immunized macaques (n = 5) were significantly higher than in unimmunized controls (n = 6) (P = 0.046).