Figure 6.

Effect of antiretroviral therapy (ART) plus Env therapeutic immunization on simian immunodeficiency virus (SIV) -specific interleukin-2 (IL-2) production by circulatory central memory CD4⁺ T cells. Freshly isolated peripheral blood mononuclear cells (PBMCs) were stimulated with SIV-specific peptides for 6 hr to measure intracellular cytokine production by central memory (CD28⁺ CD95⁺, CM) CD4⁺ T cells. (a) Env-specific production of interferon-γ (IFN-γ), IL-2 and tumour necrosis factor-α (TNF-α) by CM CD4⁺ T cells. (b) Gag- and Env-specific production of IL-2 by CM CD4⁺ T cells. *P < 0·05 and ***P < 0·001 indicate statistically significant differences of combined Env-specific cytokine responses (a) and combined Gag- and Env-specific responses (b) between the compared time-points by Wilcoxon matched-pairs signed rank test. (c, d) Correlation in Group C macaques between Env-specific IFN-γ-producing CD56⁺ NK cells with Env-specific IL-2 production by CM CD4⁺ T cells (c) and week 11 plasma viral loads (d). (e, f) Correlation in all macaques between Gag-specific IFN-γ-producing CD56⁺ NK cells with Gag-specific IL-2 production by CM CD4⁺ T cells (e) and absolute number of circulatory CD4⁺ T cells (f). Spearman's correlation analysis was used to determine statistical significance in c–f.