Figure 5. Endogenous Arg2 in CD8⁺ T cells is a cell-intrinsic regulator of their antitumor function.

(A) The scheme illustrates the experimental setting used in panels B–D, F, and G. Five days prior to adoptive T cell transfer, 0.5 × 10⁶ MC38-OVA cells were implanted s.c. into WT host. At day 0, 1 × 10⁶ to 1.5 × 10⁶ CD8⁺ T cells isolated from naive WT or Arg2^–/– mixed BM chimeric mice were adoptively transferred into the tumor-bearing mice. Control mice received no T cells. One day after T cell transfer, mice were immunized s.c. with OVA_257–264 and CpG-B. (B) Tumor growth, (C) mouse survival, and (D) tumor clearance rates at day 40 were assessed (n = 12–15). (E) Tumor growth was assessed using a setting identical to that in A, except that tumor-bearing mice received naive or 6-day preactivated CD8⁺ T cells derived from WT or Arg2^–/– OT-I mice (n = 11–12). Only mice transferred with naive cells were primed in vivo by s.c. immunization with CpG-B and OVA_257–264. (F and G) t-SNE plots showing the FlowSOM-guided metaclustering gated on (F) TCRb⁺ T cells present in the TdLNs or gated on (G) CD45⁺ cells infiltrating the tumors of WT tumor-bearing mice having received WT (left) or Arg2^–/– (right) OT-I cells. (B–E) Results were pooled from 2 or 3 independent experiments. Data is represented as mean ± SEM throughout. *P < 0.05, **P < 0.01, and ****P < 0.0001 (B and E: 2-way ANOVA) (C: log-rank Mantel-Cox test) (D: Fisher’s exact test).