SR1 CD7⁺ cells are capable of peripheral reconstitution in vivo. (A) Thymuses were harvested 10 to 12 weeks postinjection of SR1 CD7⁺ cells, and the percentage of live CD45⁺ cells and CD4 and CD8 are shown (n = 4). (B) Representative flow cytometric plots of CD3 expression on circulating human CD45⁺ cells harvested from the spleen of mice 10 to 12 weeks after injection of CD7⁺ cells (n = 6). Representative flow cytometric plots for intracellular IL-2, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α) upon in vitro stimulation. Human CD45⁺CD3⁺ cells were harvested from the spleen of mice 10 to 12 weeks postinjection of SR1 CD7⁺ cells, and stimulated for 6 hours with phorbol 12-myristate 13-acetate (PMA)/ionomycin (C) or 72 hours with CD3/CD28 (D). Percentage of cytokine-expressing cells is shown as a proportion of total human CD45⁺ cells within the thymus for individual mice. Results are from 3 independent experiments, with error bars corresponding to standard error of the mean.