Reduced numbers of donor-derived NK cell precursors inPU.1^−/− chimeras.

(A) BM cells of WT and PU.1^−/−chimeras were isolated, and lineage-positive cells were eliminated by a combination of magnetic bead depletion and electronic gating. HSCs (boxed cells) were identified by c-kit and Sca-1 expression as shown. Percentages were calculated on total BM cells. Data are representative of 4 independent experiments. (B) Lin-depleted BM cells were in parallel stained with mAbs specific for DX5-FITC, NK1.1-PE, and IL-2Rβ-APC. Absolute numbers ± standard deviation of Lin-depleted BM cells are indicated on top of the dot plots. Lin-IL-2Rβ⁺ cells were electronically gated, and their percentages are indicated. (C) The percentages of gated Lin-IL-2Rβ⁺ cells that were positive or negative for NK1.1 and DX5 are indicated. Data are representative of 3 independent experiments, including 8 WT and 5PU.1^−/− chimeras.