DC_regs suppressed LPS-induced production of proinflammatory cytokines by macrophages. (A, B) Macrophages, mDCs, or DC_regs (5 × 10⁵) were stimulated or not stimulated with LPS (1 μg/mL) for 24 hours. Alternatively, macrophages (5 × 10⁵) were stimulated or not stimulated with LPS (1 μg/mL) in the presence or absence of DCs (1.25 × 10⁵ to 5 × 10⁶), control Ig (10 μg/mL), or anti-IL-10 Ab (10 μg/mL) for 24 hours. The culture supernatants were analyzed for the production of TNF-α (A) or IL-12p40 (B). Data were expressed as mean ± SD of duplicate samples, and the results are representative of 4 experiments with similar results. Statistical analysis was performed by Student paired t test. ^*P < .01 compared with macrophages; †, compared with cell ratios of 1:0.25 or 1:0.5; ‡, for comparison between cell ratio of 1:0.25 and 1:1; §, for comparison between cell ratios of 1:0.5 and 1:1; ∥, compared with macrophages/mDCs at cell ratios of 1:1; and ¶, P < .01 compared with macrophages/DC_regs at cell ratio of 1:1. (C, D) Macrophages, mDCs, or DC_regs (5 × 10⁵) obtained from normal mice or Il10KO mice were stimulated or not stimulated with LPS (1 μg/mL) for 24 hours. Alternatively, macrophages (5 × 10⁶) were stimulated or not stimulated with LPS (1 μg/mL) in the presence or absence of DCs (1.25 × 10⁵ to 5 × 10⁶) for 24 hours. The culture supernatants were analyzed for the production of TNF-α (C) or IL-12p40 (D). Data were expressed as mean ± SD of duplicate samples, and the results are representative of 4 experiments with similar results. Statistical analysis was performed by Student paired t test. ^*P < .01 compared with macrophages; †, for comparison between normal DCs and Il10KO DCs; ‡, for comparison between cell ratios of 1:0.25 and 1:0.5; §, for comparison between cell ratios of 1:0.25 and 1:1; and ∥, for comparison between cell ratios of 1:0.5 and 1:1.