Virus-specific CD8⁺ T cells become less exhausted with increasing maturity. (A-B) The surface phenotype of HIV-specific and CMV-specific CD8⁺ T cells is shown for representative exhausted populations (PD-1⁺CD160⁺2B4⁺LAG-3⁻, PD-1⁺CD160⁻2B4⁺LAG-3⁻, and PD-1⁻CD160⁻2B4⁺LAG-3⁻) from a single HIV⁺ person by overlaying responding cells (red contour plots) on density plots of the corresponding total CD8⁺ T-cell populations for CD27 and CD45RO expression. (C-D) Maturation decreases inhibitory molecule expression on PD-1⁺CD160⁺2B4⁺LAG-3⁻ (dark purple), PD-1⁺CD160⁻2B4⁺LAG-3⁻ (purple), and PD-1⁻CD160⁻2B4⁺LAG-3⁻ (light purple) HIV-specific CD8⁺ T cells, and PD-1⁺CD160⁺2B4⁺LAG-3⁻ (dark gray), PD-1⁺CD160⁻2B4⁺LAG-3⁻ (gray), and PD-1⁻CD160⁻2B4⁺LAG-3⁻ (light gray) CMV-specific CD8⁺ T cells, in HIV⁺ persons before ART (n = 47 for HIV-specific CD8⁺ T cells; n = 60 for CMV-specific CD8⁺ T cells). The phenotypic complexity of virus-specific CD8⁺ T cells was assessed by analyzing the individual phenotypic patterns. The y-axis displays the percentage of each phenotypic pattern, the composition of which is denoted on the x-axis with + for the presence of CD27, CD45RO, and CCR7 on PD-1⁺CD160⁺2B4⁺LAG-3⁻, PD-1⁺CD160⁻2B4⁺LAG-3⁻, and PD-1⁻CD160⁻2B4⁺LAG-3⁻ virus-specific CD8⁺ T cells. The proportion of total memory CD8⁺ T cells accounted for by each phenotypic pattern, together with the median and interquartile ranges, are shown. The phenotypic patterns are grouped and color-coded according to phenotype and summarized in pie chart form; each pie slice represents the mean proportion of total memory CD8⁺ T cells for each inhibitory receptor expression pattern. Red represents CM; blue, TM; green, EM; and yellow, Eff.