Fig. 4.

Differential expression of immune checkpoint (IC) molecules on CD4⁺ and CD8⁺ T cells in mice with lung cancer. To induce lung adenocarcinoma, TC-1 cells were intravenously injected into syngeneic mice. a, b Tumor-bearing mice at 3 weeks after TC-1 cell injection and naïve control mice were sacrificed, and lymphocytes were isolated from peripheral blood (PB), spleen (SP), and lung (LG). (Left) Expression levels of PD-1, TIM-3, and TIGIT on CD4⁺ and CD8⁺ T cells were assessed. (Right) Summary of the proportions of IC molecules expressed on populations of CD4⁺ and CD8⁺ T cells in PB, SP, and LG at the tumor site. Numbers in the plot indicate percentages of the corresponding population. Data are representative of three independent experiments (n = 5 mice per group in each experiment). ns, not significant; *P < 0.05, **P < 0.01, ***P < 0.001 (Student’s t-test). The symbol above each column is the P value obtained when SP samples were compared to the corresponding samples from naïve mice (control)