Antigen-specific CD8⁺ T-cell expression of CD100 is decreased and the absolute numbers of CD100 expressing total CD8⁺ T cells, naive cells and TEMRAS correlate with p24-specific T-cell responses in untreated, viremic chronically infected individuals. Representative dot plots of (A) CMV pentamer-specific T cells in HC and (B) HIV-1–specific CD8⁺ T cells in a chronically HIV-1–infected individual. (C) Histogram of CD100 expression by pentamer-specific CD8⁺ T cells. (D) Summary of CD100 expression on antigen-specific CD8⁺ T cells in HCs and HIV-1 patients. Comparison of the (E) percentage of CD100 expression and (F) CD100 gMFI in HIV-1 infected subjects with both CMV and HIV-1–specific CD8⁺ T cells within the same individual. Correlation of absolute numbers of CD100 expressing (G) CD8⁺ T cells, (H) naive CD8⁺ T cells, and (I) CD8⁺ TEMRA cells with p24-specific T-cell responses in untreated, viremic chronically infected HIV-1 patients (n = 53). (J) Correlation of CD100⁺ CD8⁺ T cells with CD4⁺ T-cell count in both untreated early and chronically infected patients (n = 84). Statistical analysis was performed using (D) Kruskal Wallis tests with Dunn posttest, and (E-F) 2-tailed paired Student t tests. (G-J) Correlations were determined by 2-tailed nonparametric Spearman correlations.