HIV-specific CD8⁺ T-cell functionality discriminates HIV-infected nonprogressors. (A) HIV Gag-specific CD8⁺ T-cell responses in HIV-infected nonprogressors are highly functional. The black bars represent the CD8⁺ T-cell response frequency to Gag in a representative nonprogressor (subject NP8) expressing the particular combination of functions shown. Each dot denotes CD107a, IFN-γ, MIP-1β, IL-2, and/or TNF-α positivity. The panel also contains horizontal bars of different colors showing those combinations of 5, 4, 3, 2, or 1 function for reference. Responses shown are background subtracted using the 28/49d negative control. (B) HIV-specific CD8⁺ T cells are highly functional in HIV-infected nonprogressors. Each pie chart represents the mean response across the 9 nonprogressors to the 5 different HIV-antigen stimulations. For simplicity, responses are grouped by number of functions, matched to the colored bars in panelA. As shown, responses with 5 functions can be detected to each HIV antigen in the nonprogressors, and a large proportion of the responding cells express 4 functions. (C) HIV-specific CD8⁺ T cells from nonprogressors (blue boxes) have a qualitatively different functional profile compared to progressors (red boxes). The box plots represent the 10th, 25th, 75th, and 90th percentiles of the proportion of the respective functional response toward the total CD8⁺ T-cell response against HIV Gag (left) or other HIV antigens (right panels). For simplicity, only the 5+ and 4+ populations lacking IL-2 production are shown for Pol, Env, Nef, and TRVVV responses; no differences were found for those functional combinations not shown. The responses from the cohorts were standardized so that the profiles could be compared irrespective of any frequency differences. Asterisks are placed above response pairs that are significantly different: ***P ≤ .001; **P ≤ .01. Marginal differences (P ≤ .05) are designated as a single asterisk. Each dot denotes a positive response for the function indicated at the bottom left.