Lymphoma-derived IL-10 unbalances other immune suppressive subsets, exhibits antiangiogenic functions, and attenuates the response to T_reg-depleting immunotherapy. (A) Overall percentage of CD11b⁺ F4/80⁺ TAMs identified by flow cytometry in pBIC and pBIC^Δ10 tumors (t test). (B) Dot plot based on scRNA-seq data showing scaled expression levels of M1 and M2 marker genes in the macrophage population infiltrating pBIC and pBIC^Δ10 tumors. (C) Representative images of chromogenic multiplex immunohistochemistry (cmIHC; green represents GFP⁺ lymphoma cells; red, CD31) illustrating distinct CD31⁺ vascular extensions in pBIC and pBIC^Δ10 lymphomas. The tissue structure was stained with Hem. (D) Percentage of CD31⁺ vascular area over the total tissue area (t test). Slides from 3 independent mice were analyzed within each genotype. (E) Representative images of cmIHC illustrating differences in vascular morphology in pBIC or pBIC^Δ10 lymphomas. Arrowheads mark regions lacking detectable CD31 immunoreactivity and the presence of GFP-expressing lymphoma cells in apparent contact with the lumen of mosaic vessels. Continuous and robust CD31 staining is indicated by a solid line. (F) Overall percentage by flow cytometry of intratumoral MDSCs (left; CD11b⁺ F4/80^– non–double-positive [CD11c⁺ and IAb⁺]) and subsets (right) of Gr-MDSCs (Ly6G⁺Ly6C^–) or Mo-MDSCs (Ly6G^–Ly6C⁺) from total splenocytes in pBIC and pBIC^Δ10 tumoral spleens (t test). (G) Mo-MDSCs studied by flow cytometry in PBMCs from control nontumoral mice (nonimmunized Cγ1-negative littermates of pBIC mice) and tumoral models at advanced disease stages (ANOVA). (H) Heat map representation of IL-10 concentrations measured by ELISA in serum samples of pBIC and pBIC^Δ10 mice at different time points. (I) Overall percentage of T_reg cells (from the total of CD4⁺ cells) in tumoral spleens from untreated pBIC and pBIC^Δ10 mice, further compared with mice treated for 4 weeks with αCD25^NIB T_reg-depleting antibody (t test). (J) In vivo regime for αCD25^NIB treatments. (K) Flow cytometry study of PD-1⁺LAG3⁺ CD8 cell populations obtained from the spleens of mice either untreated or treated with αCD25^NIB, after 4 weeks of treatment (ANOVA). (L) Survival curves from the time of treatment in pBIC and pBIC^Δ10 mice after αCD25^NIB treatment (log-rank test). ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; d, days; Gr-MDSC, granulocytic-MDSCs; Mo-MDSC, monocytic-MDSCs; ns, nonsignificant; OS, overall survival; PBMCs, peripheral blood mononuclear cells; wk, week.