Tolerogenic dendritic cells (tDCs) increase the percentage of regulatory T cells (Tregs) in vitro. (a), Splenic CD4+ T cells (1 × 106 cells/mL) were cultured for 3 days in the presence of medium alone or combined with immature DCs (imDCs), mature DCs (mDCs), or IL-27-tDCs (2 × 105 cells/mL). The cells were labeled 72 hours later with anti-CD4, anti-CD25, and anti-Foxp3 and analyzed by FACS. FACS data are representative of 1 of 6 to 8 independent experiments (each coculture preparation was prepared from a different mouse). (b) Graphs represent the average percentages of Tregs in CD4+ splenic T cells of different groups. (c) Analysis of the mRNA levels of interferon-γ (IFN-γ), IL-17A, Foxp3, interleukin (IL)–10, and transforming growth factor-β (TGF-β) in different groups. No DCs group n = 6, imDCs group n = 8, mDCs group n = 8, and tDCs group n = 8. ∗∗P < 0.01.