Figure 7.

Blockage of PD-L1 augments the anti-tumor efficacy of IFNα in vivo

(A and B) CD14⁺ monocytes were cultured with medium or 10 pg/mL IFNα2, SK TCS, or SK TCS plus 10 pg/mL IFNα2, respectively. Two days later, the ratio of CD169⁺ cells in CD14⁺ cells (A) and the expression of PD-L1 on CD14⁺ cells (B) were determined by flow cytometry; n = 11. (C) Wild-type (WT) C57BL/6 mice were injected subcutaneously with 1 × 10⁶ Hepa1-6 cells. Then, 10 μg of IFNα-IgG or PBS (NTC) was administered intravenously on day 8, and tumoral tissues were collected on day 11; n = 10. Multiparametric flow cytometry analysis was used on of live immunocytes that were isolated from freshly dissociated tumor specimens, and PD-L1 expression levels on various myeloid cells were analyzed. (D–G) WT C57BL/6 mice were injected subcutaneously with 1 × 10⁶ Hepa1-6 cells. Then, 10 μg of IFNα-IgG was administered intravenously on days 10, 12 and 14. Meanwhile, 100 μg of anti-PD-L1 was administered intraperitoneally on days 10 and 14. Spleen tissues were collected on day 21; n = 9 or 10. (D and E) IFNγ-expressing CD8⁺ T cells were detected from tumor-bearing mice spleens. (F) Tumor size (in cm). (G) Tumor growth curve. Data represent mean ± SEM of two independent experiments. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001; NS, not significant; paired Student’s t test (A and B), multiple t test (C), unpaired Student’s t test (E), and two-way ANOVA (G).