Figure 4. CD103⁺ DCs, but not CX3CR1⁺ DCs, induce B. breve-dependent Tr1 cell differentiation.

CD103⁺ CX₃CR1⁻ CD11b⁻ CD11c⁺ DCs (CD103⁺ DCs) and CX₃CR1⁺ CD11b⁺ CD11c⁺ DCs (CX₃CR1⁺ DCs) were isolated from the colonic lamina propria, and treated with the same numbers of B. breve for 24 h. After washing, splenic naïve CD4⁺ T cells were co-cultured with B. breve-treated CD103⁺ DCs or CX₃CR1⁺ DCs in the presence of anti-CD3 mAb for 4 days. (A) T cells were then harvested and re-stimulated for 24 h to analyze IL-10 production by ELISA. *P<0.05. (B) T cells were collected, and re-stimulated with PMA and ionophore for 8 h. Intracellular expression of Foxp3 and IL-10 was then analyzed by flow cytometry. (C) C57BL/6J mice (n = 5) were fed with B. breve for 3 weeks. Then, CD103⁺ DCs were isolated from MLN and the colonic lamina propria, and co-cultured with splenic naïve CD4⁺ T cells. The co-cultured T cells were re-stimulated and IL-10 concentration in the supernatants was analyzed by ELISA. Data are representative of four independent experiments and show mean values ± S.D. of triplicate determinations. *P<0.05, **P<0.01.