Fig. 3.

Elevated DLL1 levels in the TME promote the accumulation and activation of CD8⁺ T cells in EO771 breast tumors. EO771-R1 and EO771-L1 breast tumors were prepared as described in Fig. 1. Tumor-infiltrating immune cells were analyzed by flow cytometry. The doublet/aggregated events were gated out using side scatter area versus side scatter width. Dead cells were excluded by 7-AAD staining. Lymphoid cells in CD45⁺CD11b⁻ cells were analyzed with expression of CD8 and CD4. (A and B) The proportions of tumor-infiltrating CD8⁺ and CD4⁺ T cells. (C and D) IFN-γ production in tumor-infiltrating CD8⁺ T cells. (E) The proportions of effector memory (CD8⁺CD44⁺CD62L⁻) and central memory (CD8⁺CD44⁺CD62L⁺) CD8⁺ T cells in EO771-R1 and EO771-L1 breast tumors. (F and G) IFN-γ production in tumor-infiltrating CD4⁺ T cells. The significance was determined by unpaired two-tailed Student’s t tests. Data are from one experiment representative of three independent experiments with similar results (n = 7 to 9 mice per group). All data are presented as means ± SEM, *P < 0.05, **P < 0.01, ns, no significant difference.