Generation of immature NK cells in one-step, serum-free, stromal cell–free cultures.

Lin⁻ c-kit^Lo cells were isolated from bone marrow as described in “Materials and methods” and placed in serum-free, stromal cell–free cultures containing SCF, FL, IL-7, and IL-15. Seven days later, cells were harvested and compared with freshly isolated spleen cells by flow cytometry. The top 4 plots show expression of CD3, DX5, NK-1.1, and CD94 markers on cells derived from C57BL/6 mice, whereas the lower 2 histograms illustrate the Ly49G2 on NK-lineage cells generated from BALB/c mice.