Low frequencies of HIV-specific CD8⁺ T cells in the cases exhibited significant proliferative and cytotoxic responses after 6-day stimulation that were less than those of typical LTNPs/ECs. (A) Frequencies of IFN-γ–secreting CD8⁺ T cells measured in response to peptide pools spanning the HIV-1 Nef, Gag, and Pol gene products are shown for the cases (C1, ×; C2, †; C3, ★; C4, ◊), typical LTNPs/ECs (n = 21), viremic progressors (Prog; n = 12), and Rx<50 (n = 14). (B) Frequencies of IFN-γ–secreting CD8⁺ T cells measured in response to autologous HIV_SF162-infected CD4⁺ T-cell targets are shown for the 4 cases, typical LTNPs/ECs (n = 27), viremic progressors (Prog; n = 13), and Rx<50 (n = 50). (C) Proliferation as assessed by CFSE dilution over 6 days in response to autologous HIV_SF162-infected CD4⁺ T-cell targets is shown for the 4 cases, HIV-negative controls (n = 11), typical LTNPs/ECs (n = 24), viremic progressors (Prog; n = 11), and Rx<50 (n = 55). (D-E) Total cytotoxic responses measured by GrB target cell activity (D) or ICE (E) with day 6 CD8⁺ T cells are shown for the 4 cases, HIV-negative controls (n = 11), typical LTNPs/ECs (n = 18), viremic progressors (Prog; n = 17), and Rx<50 (n = 17). Horizontal lines represent median values. Comparisons were made using the Wilcoxon 2-sample test. Only P values referring to comparisons between the responses of the cases and other groups are shown. (F) Using day 6 CD8⁺ T cells, GrB target cell activity correlates directly with ICE (n = 67). Statistical analysis was performed using the Spearman correlation.