Multilineage differentiation of human ALDH^hiLin^- cells in NOD/SCID β2M null mice. BM from a highly engrafted mouse that received transplants with 10⁴ ALDH^hiLin^- cells was stained with human-specific antibodies for markers expressed on mature hematopoietic lineages and on primitive progenitor cells. (A) Mononuclear cells were first selected (gated R1) according to forward and side scatter properties. (B) Human hematopoietic cells were selected by the expression of CD45 (gated R2) and analyzed for background staining (C), mature myeloid cell markers CD33 and CD15 (D), mature B-cell markers CD19 and CD38 (E), and mature T-cell markers CD4 and CD8 (E). CD45⁺ human hematopoietic cells were also analyzed for the maintenance of human progenitors by CD34 and CD38 expression (G) and primitive repopulating cells by CD34 and CD133 (H) coexpression. Data represent the mean ± SEM expression of various markers on the CD45⁺ human cells derived from the BM of 5 human engrafted NOS/SCID β2M null mice (n = 5).