Delta-1^ext-IgG induces PU.1 and redirects monocyte to CD1a⁺ DC development. CD34⁺ cord-blood cells were stimulated in 10% FCS (A) or in serum-free medium (B) supplemented with the basic cytokine combination SCF/Flt3L/GM-CSF. Basic cytokines were further supplemented with TGF-β1 or TNFα as indicated. FACS diagrams show the phenotype of cells stimulated with plate-bound Delta-1^ext-IgG or control. Cells were harvested at day 7, and bivariate analyses for CD1a versus Langerin, CD11b, or CD14 are displayed. Numbers in quadrants indicate the percentage of cells in that quadrant. (C) The Western blot shows endogenous PU.1 versus actin control of cells stimulated with the indicated cytokines with or without Delta-1^ext-IgG. Data are representative of 3 experiments. S indicates SCF; F, Flt3L; GM, GM-CSF; TNF, TNFα; and TGF, TGF-β1. (D) Bars represent mean percentages ± SEM of the indicated cell populations without or with Delta-1^ext-IgG. The differences between values were significant at ^*P < .05 and ^**P < .01 (paired 2-tailed t test; n = 5 independent experiments for CD1a⁺ and CD11b⁺CD1a^- and n = 4 independent experiments for CD14⁺CD1a^-).