HDAC3 inhibits the cytotoxic response early during CD8 T cell priming. 5 × 105 CFSE-labeled CD45.2+ OT-I T cells from Hdac3-KO mice or Hdac3-WT littermates were transferred into CD45.1+ TCR polyclonal recipients. Mice were immunized with OVA + poly(I:C) in PBS. Inguinal LNs draining the immunization site were collected for flow-cytometric analysis. (A–D) Kinetics of acquisition for markers of CD8 T cell effector function in OT-I T cells 48 h after immunization. Flow cytometry plots are representative of two independent experiments with five recipient mice per genotype of donor OT-I T cells transferred. (E–H) Kinetics for acquisition of markers of CD8 T cell effector function in OT-I T cells 96 h after immunization. Flow cytometry plots are representative of two independent experiments with five recipient mice per genotype of donor OT-I T cells transferred. Means ± SD are indicated (A–H). P values were calculated by two-way ANOVA. *, P < 0.05, **, P < 0.01, ****, P < 0.0001.