Fig. 1.

| CAI improves the cytotoxicity of CD8⁺ T cells and increases IFN-γ production. a B16 tumor cells and CTLs were cocultured at a ratio of 1:10 or 1:20 in the presence or absence of CAI (10 μM) for 24 h. The CTLs were preactivated with anti-CD3/CD28 beads for 48 h. The proportion of tumor cell apoptosis was determined by flow cytometry (quadrantal diagram), and the survival rate of the tumor cells in each group is shown in the bar chart. CM: culture medium (b) Contents of the cytokines in the supernatants of cocultured cells. c B16 cells were cocultured with activated CTLs at a ratio of 1:20 in the presence of vehicle (DMSO), CAI (10 μM) or IFN-γ antibody (10 mg/mL) for 24 h. The quadrantal diagrams show the proportions of tumor cell apoptosis, and the bar chart shows the survival rate of the tumor cells in each group. d, e and f) Mice were s.c. injected with 2 × 10⁵ B16 (n = 10 per group). When the average tumor size reached approximately 3 × 3 mm, the following treatments were initiated: PBS or CAI (20 mg/kg) or a combination of CAI and anti-IFN-γ antibody (250 mg/day) every 2 days for 23 days. d IFN-γ production in TILs and spleen was analyzed by flow cytometry. e Interferon content in tumor tissue was detected by ELISA. f Tumor growth curves. The data represent the mean ± s.e.m. N.S., no significant difference; **p < 0.01, ***p < 0.001 by Student’s t test (a, b, d and e) or one-way ANOVA (c and f)