Defective lymphoid commitment in the absence of Hhex. (A). Deletion of Hhex results in loss of DCs. The left panel represents flow cytometric analysis showing loss of plasmacytoid DCs (pDC) and conventional DCs (cDC) in Hhex^−/Δ mice. The right panel represents combined data showing mean + standard deviation. ***P < .001 (Student t test). (B) Schematic of experimental strategy to test repopulation capacity of Hhex^−/Δ stem cells. (C) Flow cytometric data showing contribution of LSK cells of the indicated genotypes to peripheral blood myeloid (Mac1⁺), B-cell (B220⁺CD19⁺), and T cell (CD4⁺ and CD8⁺) compartments at 12 weeks after BM reconstitution as in (B). (D) Contribution of LSK cells of the indicated Hhex genotypes to hematopoietic populations in the peripheral blood (top) (n = 10-11 per group) and spleen (bottom) (n = 7-8 per group) 12 weeks posttransplant. *P < .05; ** P < .01; *** P < .001 by Student t test. (E-F) Contribution of donor LSK cells of the indicated Hhex genotypes to the indicated stages of B-cell development (E) and T-cell development (F) at 16 weeks posttransplant. Cells were gated as HSC compartment (Lin⁻/Kit^hi/Sca-1⁺/Flt-3⁻), MPP cells (Lin⁻/Kit^hi/Sca-1⁺/Flt-3^int), LMPP cells (Lin⁻/Kit^hi/Sca-1⁺/Flt-3^hi), CLP cells (Lin⁻/Kit^int/Sca-1^int/Flt-3⁺/IL-7Rα⁺), ETP (CD4⁻/8⁻/25⁻/Kit⁺), DN2 (CD4⁻/8⁻/25⁺/Kit⁺), DN3 (CD4⁻/8⁻/25⁺/Kit⁻), DN4 (CD4⁻/8⁻/25⁻/Kit⁻), DP (CD4⁺/8⁺), CD8 (CD4⁻/8⁺), CD4 (CD4⁺/8⁻). Organs analyzed: Th, thymus; Sp, spleen; PB, peripheral blood. Data are mean ± standard deviation and are combined from 3 independent experiments. ***P < .001 by Student t test.