TIGIT expressing CD8⁺ T cells have impaired cytokine responses.

<p>Representative flow cytometry plots gated on CD8⁺ T cells showing (A) TIGIT or (C) PD-1 expression against Ki-67 from a chronically HIV-infected individual. Compiled data of Ki-67⁺ CD8⁺ T cell frequency (%) separated into (B) TIGIT⁺ and TIGIT^- or (D) PD-1⁺ and PD-1^- (<i>n</i> = 20). P values were calculated by Wilcoxon matched-pairs signed ranked test. <i>Ex vivo</i> PBMCs from chronically HIV-infected individuals were stimulated with HIV Gag peptide pool and assessed for cytokine production. (E) Representative flow cytometry plots gated on CD8⁺ T cells showing TIGIT expression and either IFN-γ, IL-2, or TNF-α content after no stimulation, stimulation with an HIV-1 Gag peptide pool, or a positive control stimulation with anti-CD3 + anti-CD28 Dynabeads. (F) Compiled data of IFN-γ, IL-2, or TNF-α CD8⁺ T cell frequency (%) from TIGIT⁺ or TIGIT^- CD8⁺ T cell compartments after HIV-1 Gag peptide pool stimulation (sample group includes; AS <i>n</i> = 4, EC <i>n</i> = 3, NC <i>n</i> = 3). P values were calculated by Wilcoxon matched-pairs signed ranked test. (G) Compiled data of TIGIT and PD-1 expression on HIV-1 Gag responding cells (sample group includes; AS <i>n</i> = 4, EC <i>n</i> = 3, NC <i>n</i> = 3). P values were calculated with repeated-measures one-way ANOVA, followed by Tukey’s multiple comparisons test (*p < 0.05; **p < 0.01; ***p < 0.001). (H) Representative flow cytometry plots of intracellular perforin and granzyme B from CD8⁺ T cells expressing or not expressing TIGIT. (I) Compiled frequency (%) of intracellular perforin⁺granzyme B⁺ content from TIGIT⁺ or TIGIT^- CD8⁺ T cell compartments (AS; <i>n</i> = 12). P values were calculated by Wilcoxon matched-pairs signed ranked test. (J) Representative flow cytometry plots gated on CD8⁺ T cells showing TIGIT and CD107a expression from TIGIT isotype control, no stimulation, HIV-1 Gag peptide pool, positive control stimulation with anti-CD3 + anti-CD28 Dynabeads. Compiled data of background corrected CD107a after (K) HIV-1 Gag peptide pool (L) anti-CD3 + anti-CD28 Dynabead stimulation in TIGIT⁺ or TIGIT^- CD8⁺ T cell compartments (AS; <i>n</i> = 10). P values were calculated by Wilcoxon matched-pairs signed ranked test.