Fig. 5: PD-L1 blockade reactivates T cells in tumor microenvironment for tumor control.
a, b C57BL/6 mice (n = 6, except day 14 FTY720 + anti-PD-L1 n = 5) were inoculated with 2.5 × 105 MC38-OVA cells and treated with (a) 200 μg IgG or anti-PD-L1 on days 8 and 12, or (b) 250 μg IgG or anti-PD-L1 on days 14 and 18. Mice were also treated with control or FTY720 the same day as antibody treatment. Tumor growth curves were shown. ***p(8: IgG vs anti-PD-L1) < 0.0001; ***p(8: anti-PD-L1 vs FTY720+anti-PD-L1) < 0.0001; ***p(14: IgG vs anti-PD-L1) < 0.0001. c Mice (n = 4, except day 14 FTY720 + anti-PD-L1 n = 3) were treated as in 5a and 5b. IFN-γ+ CD8 T cells in tumor tissues were measured by flow cytometry on day 13 (for day 8 treatment group) or on day 19 (for day 14 treatment group). *p(8: IgG vs anti-PD-L1) = 0.0462; *p(14: IgG vs anti-PD-L1) = 0.0443; *p(14: FTY720+IgG vs FTY720+anti-PD-L1) = 0.0119; *p(8: anti-PD-L1 vs FTY720+anti-PD-L1) = 0.0245. d CD11c-cre;Pdl1fl/fl or control mice (n = 14 Cre−, 15 Cre+) were inoculated with 5 × 105 MC38 cells. Viability of DCs was analyzed by flow cytometry on day 14. *p = 0.0322. e DCs purified from conditional knockout mice or B16 cells were treated with IFN-γ for 96 h. Cell viability was determined by MTT assay (n = 3 cells). **p(Cre-) = 0.0048; *p = 0.0101; **p(B16) = 0.0012. f DCs isolated from spleens of CD11c-cre;Pdl1fl/fl or control mice were loaded with OT-1 peptide and incubated with activated OT-1 T cells at an E:T ratio of 3 for 4 h. Cell death of cDC1 and cDC2 cells were measured by flow cytometry (n = 6 -T cells, 3 + T cells). **p = 0.0067; ***p(-T) < 0.0001; ***p(+T) < 0.0001. Data are shown as mean + SEM (a and b) or mean ± SEM (c–f) and are representative of two independent experiments (a, b, c, e, and f) or pool of four independent experiments d. n.s., not significant; *p < 0.05; **p < 0.01; ***p < 0.001 determined by two-way ANOVA in (a and b) or by unpaired two-tailed Student’s t test in (c–f). Source data are provided as a Source Data file.
