IL-6 blocks cDC1 development by acting the Zeb2 −165 kb Δ1+2+3 enhancer. (A) CDPs from WT mice or Zeb2^ZEB2-EGFP/+ reporter mice were sort-purified and cultured with Flt3L with (red) or without (blue) IL-6 (25 ng/ml) for the indicated time, and analyzed by FACS for EGFP expression. Numbers indicate the MFI for EGFP of cells. The line graph (lower left) shows the ratio of the ZEB2-EGFP MFI and WT MFI at each time point. (B) WT and Δ1+2+3 mice were inoculated i.p. with EL4-empty or EL4-IL-6 (10⁶ cells) and analyzed after 14 d. Shown is FACS analysis of splenocytes gated as MerTK⁻ B220⁻ SiglecH⁻ cells. (C and D) Bar-scatter graphs for (C) the splenic MerTK⁻ B220⁻ SiglecH⁻ cells described in B and (D) the splenic MerTK⁻ B220⁻ SiglecH⁻ MHCII⁺ CD11c⁺ cells described in the main Fig. 4 F. (E) WT and Δ1+2+3 mice inoculated in B were analyzed for DC progenitors in the BM. Shown is FACS analysis of Lin⁻ BM cells. Numbers indicate the percentage of cells in the indicated gates. (F) Bar-scatter graphs for cells described in E for WT (red) and Δ1+2+3 mice (gray; average % ± SD). *P < 0.05, **P < 0.01, ***P < 0.001 (Student’s t test).