Analysis of early cytokine secretion by HIV-1–specific CD8 T cells shows that IL-2, but not IFN-γ, distinguishes controllers from treated or untreated progressors. (A-B) Summary data of the mean magnitude of IFN-γ (A) and IL-2 (B) secretion by HIV-1–specific CD8 T cells after a 6-hour stimulation with panels of individual HLA class I–matched HIV-1 epitopes. Each column corresponds to a study participant. (C-D) Statistical analysis of mean IFN-γ (C) and IL-2 (D) early (6 hours) secretion among the 3 groups of HIV-1–infected subjects of the discovery cohort (n = 64) Mean IFN-γ responses based on HLA-I restriction in all patients. HC indicates HIV-1 controllers; CP, chronic progressors; and ARTC, ART-treated subjects. (E-F) Statistical comparison of means early IFN-γ (E) and IL-2 (F) responses to epitopes restricted by protective and nonprotective HLA-I alleles in all subjects. (G-H) Statistical analysis of early IFN-γ (G) and early IL-2 (H) responses stratified by protective versus nonprotective HLA-I alleles in HC, CP, and ARTC subjects. Throughout the figure, HC data are represented in blue, CP in red, ARTC in green, protective HLA class I alleles (B*5701/03, B*2705 and B*5801) in purple, and nonprotective HLA I alleles in orange. All comparisons of adjusted means were done using generalized linear models controlling for clustering within subjects. Vertical interval bars correspond to the SEM.