Engraftment of drug-resistant human PBPCs in NOD/Scid mice. A representative highly engrafted NOD/Scid mouse transplanted with 400 × 10³ drug-resistant PBPCs and 1 × 10⁶ L87/4 stromal cells was analyzed 6 weeks after transplantation by three-color flow cytometry. The percentage of positive cells per each quadrant is indicated. Cells were stained with Cy-C–labeled anti-human CD45 antibody and compared with cells stained with Cy-C isotype control. Dead cells were excluded by their intense 7AAD staining, and viable cells were gated according to their human CD45 expression (horizontal line in the histogram). Sixty-one percent of CD45⁺ human cells were present in the BM of this mice. As shown in the contour plots, among these CD45⁺ cells 19% (corresponding to 11% of all cells) were CD13⁺ (myeloid), 53% (corresponding to 32% of all cells) were CD19⁺ (lymphoid), 1% were CD34⁺/CD38⁻ (early hematopoietic progenitors), 2% were CD61⁺ (megakaryocytic), and 5% were glycophorin A⁺ (erythroid).