Perforin upregulation does not define HIV-2 control and high cytotoxic potential is not a feature of HIV-2–specific CD8⁺T cells. (A) CD8⁺ T cells coexpressing perforin and IFN-γ are detectable following SEB stimulation, with varying proportions observed following HIV-2 Gag stimulation (example plots). (B) No difference was observed between HIV-2 controllers (n = 33) and viremic subjects (n = 27) in the degree of perforin coexpression (with IFN-γ, TNF-α, IL-2, or CD107a) following stimulation with overlapping Gag peptides (2-tailed Mann-Whitney U test). Displayed are medians and upper IQR. (C) Comparison of cytolytic markers on bulk CD8⁺ and HIV-2 Gag-specific CD8⁺ T cells (n = 25 tetramer-positive populations from 21 HIV-2 subjects: 16 controllers and 5 viremic donors; 2-tailed Wilcoxon matched pairs test). Values from viremic donors are highlighted in red. (D) Comparison of cytolytic markers on different virus-specific CD8⁺ T cells (Kruskal-Wallis test with Dunn’s post test for multiple comparisons). Bars represent medians. **P < .01; *P < .05. NS, not significant.