IKDCs develop efficiently from CD62L⁺ lymphocyte progenitors. (A) LSPs, ELPs, CMPs, and CLPs were sorted from Thy1.1 congenic RAG-1/GFP reporter mice, and 5 × 10³ cells of each were transferred to sublethally irradiated recipients. Flow cytometry analyses were then performed 16 days after transplantation. Absolute numbers of donor-derived pDC (B220⁺ CD19⁻CD11c⁺ Ly6C⁺), IKDC (B220⁺ CD19⁻CD11c⁺ Ly6C⁻ NK1.1⁺), and NK (NK1.1⁺ CD11c⁻) BM cells per femur are given (* denotes significant differences [P < .05]). (B) LSPs (10³/well) were placed in OP9 cocultures with Flk-2/Flt-3 ligand and IL-15. They were subcultured to fresh stromal cell monolayers after one week, and gated B220⁺CD19⁻CD11c⁺ Ly6C⁻ cells were assessed for NK1.1 expression by flow cytometry at the indicated intervals.