Delta-1 enhances the development of bone marrow–derived committed lymphoid progenitor cells into pDCs. Common lymphoid progenitor cells were purified from bone marrow using flow cytometric sorting of Lin^– CD34⁺ CD10⁺ cells. The control Lin^– CD34⁺ CD10^– cells were also obtained and tested. Cells were seeded onto the indicated OP9 stroma cells lines in the presence of FL and IL-7. The progeny was harvested at day 14 and analyzed by flow cytometric analysis for expression of CD19, CD14, and BDCA-2 markers. Numbers indicate the percentage of each subset in quadrants.