Peripheral human immune system reconstitution in HIS versus HIS-SGM3 mice. HIS mice and HIS-SGM3 mice were generated by transplantation of human CD34⁺ HSCs into newborn NSG (NOD/SCID/IL2Rγ^null) mice and NSG mice transgenic for human GM-CSF, IL-3, and SCF (NSG-SGM3). Eight and 12 weeks after transplantation, blood was analyzed for human immune system reconstitution by flow cytometry. (A) Isolated leukocytes from HIS (◇) and HIS-SGM3 (♦) mice were counterstained with anti-mouse CD45 and anti-human CD45 antibodies to determine the overall human immune cell chimerism. Within the human CD45⁺ cell population, the frequency of T cells (B), B cells (C), and myeloid cells (D) in HIS versus HIS-SGM3 mice was determined. (E) Representative fluorescence-activated cell sorter dot plots. Unpaired Student t test: *P ≤ .05; **P ≤ .005; ***P ≤ .0001.