Fig. 3

Combination therapy reverses the myeloid cell-mediated immunosuppression and promotes infiltration of activated DCs and T cells. a Peritoneal cell suspensions from tumor-bearing mice treated with vehicle (Veh); chemotherapy (Chemo); anti-IL-10, 2′3’-cGAMP, and anti-PD-L1 immunotherapy (IT); or both Chemo and IT (Combo) were assessed by flow cytometry 4 days after initiation of treatment. a, b Decreased numbers of myeloid cells with immunosuppressive phenotypes are observed upon Combo treatment. a Decreased numbers of F4/80⁺ macrophages are observed upon treatment with immunotherapy (IT and Combo) (b) Flow cytometry gating of subsets of ARG1⁺IL-10⁺ myeloid cells are shown as scatter plots and quantified at right. c, d Increased numbers of mature dendritic cells are observed upon Combo treatment. c Flow cytometry gating of subsets of CD11c⁺ dendritic cells are shown as scatter plots and quantified at right. Numbers of CD11c⁺ cells expressing co-stimulatory molecules are quantified. d STING activation is pharmacodynamically confirmed by increased median fluorescence intensity of IRF3. e The adaptive immune system is also impacted by Combo therapy. Flow cytometry gating of subsets of CD3⁺ T cells are shown as scatter plots and quantified at right. Increased numbers of CD4⁺ T cells expressing the activation marker CD69, the cytolytic molecule CD107a, and the pro-inflammatory cytokine IL-2 are observed. Increased numbers of CD8⁺ T cells expressing the cytolytic molecule GZMB are shown. The experiment was performed twice with n = 4 biological replicates. Statistics were calculated using one-way ANOVA with Tukey’s multiple comparisons test. Data are presented as mean ± SEM * p ≤ 0.05, ** p ≤ 0.01, *** p ≤ 0.001, **** p ≤ 0.0001