Effect of cytokine stimulation on the engraftment of CD34⁺ cells in NOD/SCID mice. (A) Engraftment was assessed at 4 to 6 weeks after transplantation in mice that received freshly isolated CD34⁺ cells or cultured cells (0.5 or 1.0 × 10⁶ cells/animal). Bone marrow cells were assayed for human colony formation (as detailed in “Materials and methods”). Data are given for each animal in 2 independent experiments, and the median for each group is indicated. (B) Lineage-specific engraftment of fresh (⋄) and cultured cells () was assessed by flow cytometry. The percentage of huCD45⁺ cells that also expressed human lymphoid, myeloid, and progenitor surface markers is shown. Data are given for each animal from 2 independent experiments. **P < .01 compared with fresh cells; Mann-Whitney U test.