Increased immunosuppressive phenotype and activity of CD11b⁺/Ly6C^high monocytes from D6^−/− mice. [³H]-thymidine incorporation (A) and IFN-γ production (B) by OVA peptide-stimulated OT-I splenocytes cultured alone (gray bar) or in the presence of D6^−/− (black bar) and WT (white bar) CD11b⁺/Ly6C^high monocytes at indicated ratio. *P < .05, OT-I treated with D6^−/− versus WT cells. #P < .05, treated OT-I versus basal proliferation. (C) Mean fluorescence intensity fold increase of markers on gated CD11b⁺/Ly6C^high monocytes from spleen of D6^−/− (black bar) versus WT (white bar) mice (n = 7 mice/group). (D) Mean fluorescence intensity fold increase of CD11b expression on circulating CD11b⁺/Ly6C^high monocytes of D6^−/− (black bar) and CCR2^−/− (gray bar) versus WT (white bar) mice (n = 7 mice/group) in basal conditions or 2 days after CFA. #P < .05, CFA versus basal condition. (E) Fold increase of ARG1 and COX2 mRNA expression in CD11b⁺/Ly6C^high monocytes sorted from spleen of D6^−/− (black bar) versus WT (white bar) mice. (F) Recovery of OT-I splenocyte proliferation in the presence of D6^−/− (black bar) and WT (white bar) CD11b⁺ cells after treatment with indicated inhibitors. Data are mean ± SD of 3 independent experiments. *P < .05, D6^−/− versus WT cells. #P < .05, inhibitors treatment versus medium. (G) Induction of ARG1 and COX2 expression in BMDM from WT (white bar) and CCR2^−/− (gray bar) mice cultured for indicated times in presence of hCCL2 (10 ng/mL). *P < .05, CCL2-treated versus control cells. **P < .005, CCL2-treated versus control cells.