Fig 1: Hyper-production of IL-6 by Cblb-/- macrophages promotes a pathogenic Th17 response(A) Th1/Th17 cell differentiation in co-cultures of 2D2 T cells with BMDMs or BMDCs from WT and Cblb-/- mice (n = 3/group) in the presence of heat-killed M.tb and MOG35-55. ***p < 0.001; Student t test.(B) Th1/Th17 cell differentiation in co-cultures of 2D2 T cells with BMDMs from WT and Cblb-/- mice (n = 3/group) in the presence of heat-killed M.tb and MOG35-55 with or without pretreatment with mitomycin C. ***p < 0.001; Student t test.(C) Flow cytometric analysis of IL-6-producing cells of dLNs of WT and Cblb-/- mice (n = 3/group) on day 8 after immunization with MOG35-55 in CFA, and stimulated with PMA/ionomycin. The gating strategy and representative plots see Figure S5. **p < 0.01; Student t test.(D) ELISA of pro-inflammatory cytokines (TNF-a, IL-6, IL-10, IL-12p40, IL-1ß, TGF-ß, IL-23, and IL-21) by BMDMs from WT and Cblb-/- mice (n = 5/group) stimulated with heat-killed M.tb. *p < 0.05, ***p < 0.001; Student t test.(E) Th1/Th17 cell differentiation in co-cultures of 2D2 CD4+ T cells with BMDMs from Cblb-/- mice that had been treated with Il6 or control siRNA. IL-6-producing macrophages of Cblb-/- mice treated with Il6 (n = 4) or control siRNA (n = 4) were also determined. The mean fluorescent intensity (MFI) determined by flow cytometry indicates the expression level of IL-6 in CD4- macrophages of Cblb-/- mice treated with Il6 or control siRNA. ***p < 0.001; Student t test.(F) Clinical scores of Cblb-/- mice immunized with MOG35-55 in CFA in the treatment with or without Il6 siRNA (n = 5) or control siRNA (n = 5) on day 1, 3, and 7 via tail vein injection. **p < 0.01; Mann-Whitney U test.(G) Flow cytometric analysis of Th1/Th17 responses and IL-6-producing cells in dLN cells from Cblb-/- mice treated with Il6 (n = 3) or control siRNA (n = 3) via tail vein injection as in F on day 8 after immunization with MOG35-55 in CFA. MFI determined by flow cytometry indicates the expression level of IL-6 in F4/80+ cells from dLNs of Cblb-/- mice treated with Il6 (n = 3) or control siRNA (n = 3). *p < 0.05; Student t test.(H) Clinical scores of Cblb-/- mice immunized with MOG35-55 in CFA in the treatment with or without Il6 siRNA (n = 5) or control siRNA (n = 5) on day 8, 11, and 15 via tail vein injection. Bracket: the total number of gated CD4+ T cells. Data are representative of three independent experiments (A, B, E, F, and G) and representative of two independent experiments (C-D).