HIV-specific CD8⁺T cells express low IRF4. PBMCs from HIV⁺ subjects were stimulated with 1 μg/mL CEF peptides or HIV peptides for 18 hours. (A) Expression of IRF4 and CD137 by CD8⁺ T cells. (B) MFI of IRF4 and CD137 expression by CD8⁺ T cells specific for CEF and HIV peptides (n = 13). (C) viSNE analysis showing differential marker expression by CD8⁺ T cells specific for CEF peptides (upper panels) or HIV peptides (lower panels). A representative result of 13 samples (gated on CD8⁺CD69⁺ T cells) is shown. Red arrows indicate a cell population uniquely observed in the HIV-specific CD8⁺ T cells. Blue arrows indicate a cell population shared between CEF- and HIV-specific CD8⁺ T cells. (D) CD27 and CD25 expression by IRF4⁺CD137⁺ CD8⁺ T cells in PBMCs stimulated with CEF or HIV peptides. A representative result of 11 samples is shown. (E) MFI of CD25 (left panel) and percentage of CD25⁺ (right) by IRF4⁺CD137⁺ CD8⁺ T cells in PBMCs stimulated with CEF or HIV peptides (n = 11). (F) MFI of CD27 (left panel) and percentage of CD27⁺ (right panel) by IRF4⁺CD137⁺ CD8⁺ T cells in PBMCs stimulated with CEF or HIV peptides (n = 11). *P < .05, **P < .01, ***P < .001, ****P < .0001, paired Student t test.