Figure 5.

PD-L1 blockade with concurrent CD4⁺ T cell depletion induced vascular normalization and tumor regression in MCA38 colorectal tumors. C57BL/6 J mice were inoculated with 2 × 10⁵ MCA38 colon tumor cells. When MCA38 colon tumors reached 4-5 mm in diameter (day 0), mice were randomly assigned to 4 groups and treated with anti-CD4 antibody on days -1, 1, and 8. On day 0, mice were treated with anti-PD-L1 (10 mg/kg) or IgG (10 mg/kg) antibody, every 3 days for 3 doses. On day 9 post anti-PD-L1 treatments, mice were intravenously injected with 200 μg/mouse Hoechst 33342, and tumor tissues were harvested after 5 minutes of the injection. (a) Tumor volumes were shown in each time point for each group. (b) Representative figures showing Hoechst 33342-stained areas (blue) and immunohistochemical staining of CD31 (red). Scale bars: 100 μm. (c) Total tumor blood vessel density and Hoechst 33342 perfused area were quantified. Significant differences were determined by one-way ANOVA. Data were from one experiment representative of two independent experiments with similar results (n = 6 − 8 mice per group). Data were shown as means ± SD. ^∗P < 0.05, ^∗∗P < 0.01, ^∗∗∗P < 0.001.