PD-1⁺CD8⁺ T cells from TP patients express an exhausted phenotype. (A) Histogram plots of CD38, HLA-DR, and CD95 expression on PD-1⁺CD8⁺ T cells from representative individuals in each group. (B) Representative histogram plots of GrA, GrB, and perforin expression on PD-1⁺CD8⁺ T cells in subjects from each group. Open histograms indicate the staining of isotype controls; filled histograms, the staining of selected markers. (C) Percentage of CD38, HLA-DR, CD95, granzyme A, and granzyme B expressed on PD-1⁺CD8⁺ T cells from subjects in each group. Error bars indicate standard deviation. (D) Percentage and mean fluorescence intensity (MFI) of perforin expressed on PD-1⁺CD8⁺ T cells in subjects from each group. P values are shown. Error bars indicate standard deviation. (E) Representative expression of CD38, HLA-DR, and perforin on HIV-specific CD8⁺ T cells from LTNP (n = 5) and TP individuals (n = 6). Values in the upper right quadrant represent the percentage of CD8⁺ T cells that express each marker.