Fig. 1: T cell activation and function require VRACs.

a, b T cell size upon activation in vivo evaluated by forward scatter (FSC) on flow cytometry. OT-I and OT-II (labeled by CellTrace Violet before transfer) or P14 cells (CD45.1⁺) obtained from spleen after activation by antigen (OVA, ovalbumin or LCMV Armstrong) at indicated time (day 2 after OVA injection for (a) day 3 after infection for (b)) (OT-I, n = 3 mice/group; OT-II, n = 4 mice/group; P14, n = 10 mice/group). c, d OT-I CD8⁺ T cell activation monitored by CD69 and CD25 expression. Splenic OT-I CD8⁺ T cells were stimulated by a variety of doses of N4 peptide ex vivo for 6 h, ±DCPIB (25 μM) gated on TCRβ⁺ CD8⁺ Vα2⁺ (n = 3 replicates/mouse). e Cell size of T cells activated as in panel c, measured by flow cytometry 24 h after activation (n = 3 replicates/mouse). f T cell activation assessed by CD69 and CD25 expression. Splenic CD4⁺ and CD8⁺ T cells were activated by anti-CD3ε (0.1 μg/ml) or ConA (1 μg/ml) for 6 h ex vivo, with or without DCPIB (25 μM) (n = 4 mice/group). g–k Signaling, activation, proliferation, cytokine production, and nutrition markers in OT-I CD8⁺ T cell activated by N4 peptide at indicated concentration in vitro, ±DCPIB, examined by intracellular flow cytometry. Phosphorylation of S6 (p-S6^S240/244) (stimulated for 6 h) and MAPK (p-ERK^T202/Y204) (stimulated for 2 h) (g), Nur77 (stimulated for 6 h) (h), proliferation shown by CFSE dilution (activated for 48 h) (i), TNFα and IFNγ production (activated for 6 h) (j), CD98 and CD71 expression (activated for 6 h) (k) (n = 3 replicates/mouse for g–k). Representative flow cytometry plots were shown on the left and the corresponding quantification on the right (c, e–k). Data are representative of two (a, h–k), three (c–e, g), or more (b, f) independent experiments. Unpaired two-sided t-test was used in (a, b, d, f–h, j, k). Two-way ANOVA with Bonferroni’s post-hoc test were in (c, e, i). Data are presented as mean ± SEM. Source data are provided as a Source Data file.