Phenotype of human NK cells in BM of growth-factor–treated NOD/SCID mice. Two months after transplantation of CB CD34⁺ cells, NOD/SCID mice were treated with combinations of growth factors (A) for 7 consecutive days, and BM, spleen, and PB cells were analyzed 1 day later by flow cytometry. (A) Human NK cells in untreated control (no growth factor [GF]) and growth-factor–treated mice were detected by staining with the human leukocyte marker CD45 and the NK-cell–specific marker CD56. Analysis was performed with total mononuclear cells; numbers indicate the percentages of total BM cells. (B) Human NK cells were characterized by staining with antibodies against CD56 and the indicated NK surface marker. Numbers indicate the percentages of human CD45⁺ cells. For comparison, human NK cells from (C) CB and (D) PB were stained with antibodies against CD56 and CD16 (gated on lymphocytes) and NKp46 (gated on CD56⁺ cells). The thin line indicates staining with isotype-matched control antibody. (E) NK cells in PB of NOD/SCID mice treated with IL-15 and FL. Numbers indicate the percentages of human CD45⁺ cells.