Role of the B7 family in the ability of systemic and MLN CD11c⁺ DCs to prime antigen-specific naive CD4⁺Foxp3^– T cells. (A) Expression of the indicated molecules on Sp or MLN CD11c⁺ DCs in WT mice was analyzed by flow cytometry. Data are represented by a histogram, and numbers represent mean fluorescence intensity. Data are representative of 4 independent experiments. (B) Production of IL-6 (left panel) and TGF-β1 (right panel) by Sp or MLN CD11c⁺ DCs in WT mice stimulated or not stimulated with CpG ODN for 18 hours measured by ELISA. *P < .01 compared with Sp CD11c⁺ DCs. Data are the mean ± SD, and the results are representative of 4 independent experiments. (C-G) Proliferative response of Sp KJ1-26⁺Foxp3^EGFP− T cells to Sp or MLN CD11c⁺ DCs obtained from WT mice (C), Cd80/Cd86^−/− mice (D), B7h1^−/− mice (E), B7dc^−/− mice (F), and B7h2^−/− mice (G) in the presence or absence of OVA protein (left panel) or OVAp (right panel) was measured by [³H]thymidine incorporation. *P < .01 compared with Sp CD11c⁺ DCs. Data are the mean ± SD, and the results are representative of 4 independent experiments.