Figure 1.

Characterization and distribution of tissue-resident CD8⁺ T-cells in the rectosigmoid mucosa of chronically HIV-1-infected and seronegative participants. (a) Representative flow cytometry plot displaying surface staining of tissue-resident markers and gating strategy used to identify live, CD3⁺, tissue resident CD8⁺ T-cells as CD103⁺CD69⁺S1PR1⁻ in blood (red) and rectosigmoid mucosa (blue). (b) Differences in the frequency of CD103⁺CD69⁺S1PR1⁻ CD8⁺ T-cells between blood and rectosigmoid mucosa across HIV-1 disease status. (c) Representative flow cytometry plot demonstrating the difference in CD103 fluorescence intensity and CD69 expression in rectosigmoid naïve (T_naive, aqua), central memory (T_CM, orange), transitional memory (T_TM, green), effector memory (T_EM, purple), and effector (T_EFF, red) CD8⁺ T-cells. Numbers in parentheses indicate the percentage of the memory subset in the total rectosigmoid CD8⁺ T-cell population; colored numbers indicate frequency of the memory subset in each quadrant. Memory/effector subsets were first identified by differential expression of CD45RO, CD27, and CCR7 as described in the text. (d) Comparison of the frequencies of rectosigmoid CD103^High and CD103^Low CD69⁺S1PR1⁻ CD8⁺ T-cells within each memory subset, or (e) between memory subsets in a combined group of chronically HIV-1-infected and seronegative participants. Horizontal bars represent median, whiskers indicate interquartile ranges with the level of significance shown with asterisks as follows: * P <0.05, ** P <0.01, *** P <0.001, **** P <0.0001.