Figure 5.

Anti-PD-L1 antibody delays tumor progression of the C1498 mouse model by impairing the expansion of Treg cells. (A) BM smears were stained with Wright's stain, and representative images and statistical data of immature leucocyte cells were shown. The scale bars equal 10 μm, and arrows indicate immature leucocyte cells. (B) Statistical data of the expression of c-Kit in BMMNCs were shown. (C) Representative overlay histograms and statistical data of the expression of PD-L1 of BMMNCs were shown. Gray-filled indicate isotype-matched control, and black solid lines indicate antibody staining. (D) The frequencies of Treg cells and PD-1⁺ Treg cells were dramatically increased in the BM microenvironment of C1498-injected mice, and blockade of PD-1 signaling by anti-PD-L1 antibody attenuated drastically the expansion of Treg cells and PD-1⁺ Treg cells in BM. Images shown were representatives of 5 individual mice each group, and statistical data were analyzed using ANOVA. NS stands for not significant.