Representative flow cytometric analysis of human cell engraftment of an NSG mouse transplanted with human double-unit CB and gated on live cells. (A) Fluorescence-activated cell sorter analysis of the murine BM, spleen, and thymus after staining with PE-conjugated anti–human CD45 antibodies. (Bottom panel) Percentage of human CD45⁺ cells (51.8% in BM, 32.5% in spleen, and 7.1% in thymus). Analysis of murine BM revealed that the majority (71%) of human CD45⁺ cells were CD19⁺ (B lymphocytes), 6% CD33⁺ (myeloid cells), 3% CD34⁺, and less than 1% CD56⁺ (NK cells; data not shown). Staining for monocytes, erythroid cells, and megakaryocytes was not performed. (B) Human T-cell engraftment in the murine thymus. Of the human CD45⁺ cells, the majority were CD4⁺/CD8⁺.