Human CD45⁺ cell chimerism and CD3⁺ T-cell development in the blood of newborn-engrafted mice at 12 weeks of age. Nonirradiated NSG and NSG-Tg(hu-mSCF) and 100-cGy irradiated NSG and NSG-Tg(hu-mSCF) newborn mice were engrafted with human HSCs as described in “Engraftment of mice human HSCs.” Mice were analyzed by flow cytometry for the percentage of human CD45⁺ and the percentage of human CD45⁺ cells that were CD3⁺ in the blood at 12 weeks of age. (A) Percentage of human CD45⁺ cells. (B) Percentage of human CD45⁺ cells that were CD3⁺. No significant difference between groups was observed.