(A) GSEA plots of human CD4⁺ CTL-specific gene sets (containing 517 genes) in activated HDAC1^cKO-HDAC2^HET CD4⁺ T cells relative to activated WT CD4⁺ T cells. The barcode indicates the location of the members of the gene set in the ranked list of all genes. (B) Flow cytometry analysis showing CD4, CD8α, IFN-γ, and granzyme B expression in naive human CD4⁺ and CD8⁺ T cells (right panel) activated with CD3/CD28 Dynabeads for 5 days, for the last 24 hours in the presence of DMSO (left panel) and MS-275 (middle panel), respectively. (C) Summary of experiments described in A. Diagrams depict the percentages of activated CD4⁺ and CD8⁺ T cells, respectively, expressing CD8α, IFN-γ, and granzyme B. (D) Histogram panel depicts RUNX3 expression in activated CD4⁺ T cells (as described in A) treated with DMSO (upper panel) or MS-275 (middle panel) for 24 hours and untreated CD8⁺ T cells as staining control (lower panel). (E) Summary of the experiment described in C. Diagram depicts the FC of MFI of RUNX3 expression in activated CD4⁺ and CD8⁺ T cells, respectively. (F and H) Flow cytometry analysis showing IFN-γ, granzyme B, and EOMES expression on human Th1 cells cultured in the absence (control) or presence of pentanoate. Diagrams depict the summary of (G) the percentages of IFN-γ⁺ and IFN-γ⁺GZMB⁺ human Th1 cells, respectively, as well as (H) MFI of EOMES expression in human Th1 cells. Data are representative (B, D, F, and H) or show a summary (C, E, F, G) of 5 (B and C for CD8α), 4 (B–D for IFN-γ, GZMB, RUNX3), or 3 (H) human donors who were analyzed in 2 (F–H), 5 (B and C for CD8α), or 4 (B–E for IFN-γ, GZMB, RUNX3) independent experiments. Numbers indicate the percentages of cells in the respective quadrants or gates (B and F) or MFI (D). (D) The dotted vertical lines indicate the peak of the WT histogram (for MFI). (C, E, G, and H) Each symbol indicates 1 human donor. Horizontal bars indicate the mean. *P < 0.05 (paired 2-tailed Student’s t test).