Positive correlation between T-bet and the expression of both perforin and Grz B within activated CD8⁺ T cells. (A-B) The proportion of Nef-specific perforin (A) and Grz B (B) expression was plotted against the fraction of the response that was T-bet^bright within all therapy-naive subjects (ECs, blue; CPs, red). Spearman correlation tests (nonparametric; 2-tailed) were performed to determine statistical significance as indicated. Only those subjects in whom a Nef-specific response was detected are plotted. (C) Relative levels of T-bet expression are shown within perforin⁺IFN-γ⁺ (gray) and perforin⁻IFN-γ⁺ (red) CD8⁺ T cells from an example Nef-specific response. (D) T-bet expression profile of all perforin⁺ and perforin⁻ Nef-specific CD8⁺ T cells (as identified by staining for IFN-γ, TNFα, or CD107a) was determined among ECs. (E) Relative levels of perforin expression are shown within T-bet^brightIFN-γ⁺ (blue) and T-bet^dull/negIFN-γ⁺ (orange) CD8⁺ T cells from an example Nef-specific response. (F) The degree of perforin and Grz B positivity was determined for all T-bet^bright and T-bet^dull/neg Nef-specific CD8⁺ T cells (as identified by staining for IFN-γ, TNFα, or CD107a) among ECs. (D and F) Mann-Whitney tests (nonparametric; 2-tailed) were performed to determine statistical significance. ***P < .001. Bars represent the means and error bars indicate SDs.