The developmental defect of CD4⁺ DCs in the absence of miR-142 is cell intrinsic. (A) Schematic experimental outline of mixed BM reconstitution experiment. (B) Flow cytometric analysis of miR-142^+/+ (CD45.2)/WT (CD45.1) > WT (CD45.1) and miR-142^−/− (CD45.2)/WT (CD45.1) > WT (CD45.1) chimeric animals 8 weeks after transplantation for contribution of distinct miR-142 genotypes to the 3 cDC populations (left panel) and BM precursors, respectively. For miR-142^+/+/WT > WT mice: CD45.1/2 ratios: for CD8α⁺ DCs, 0.97 ± 0.31; for CD4⁺ DCs, 2.01 ± 0.64; for DN DCs, 1.03 ± 0.39; for miR-142^−/−/WT > WT mice: CD45.1/2 ratios: for CD8α⁺ DCs, 0.26 ± 0.07; for CD4⁺ DCs, 5.48 ± 1.15; and for DN DCs, 0.84 ± 0.17. CD45.1/CD45.2 ratios were calculated for each investigated cell population. Values > 1 indicate out-competition of the mutant by WT (CD45.1) cells, whereas values < 1 show an advantage of miR-142^−/− (CD45.2) cells. Representative results from 1 of 2 independent experiments are shown (means ± SD) with at least 4 animals in each group. SDLN indicates skin draining lymph nodes. (C) Mean fluorescence intensity (MFI) of CD40, CD80, and MHCII expression on miR-142–competent (CD45.1⁺) and miR-142–deficient (CD45.2⁺) CD4⁺, CD8α⁺, and DN DCs isolated from mixed chimeras. Representative results from 1 of 2 independent experiments are shown (means ± SD) with 3 animals in each group.