Tissue distribution and extent of differentiation of post-BMT T-lineage progenitors. B6 mice were lethally irradiated and reconstituted with Ly5^SJL BM cells. Three weeks later, cell suspensions from the spleen, MLNs, inguinal lymph nodes, BM, liver, and thymus were assessed by flow cytometry for the presence of donor-derived cells with phenotypic characteristics of T-lineage progenitors (SpT cells, as defined in Figure 2). The 3-week time point was chosen to evaluate the overall extent of prethymic differentiation. Data are representative of 2 experiments. Numbers indicate the percentage of cells in the boxed region. (A) Presence of donor-derived Lin^–Thy1.2⁺ pre-T cells in the spleen, lymph nodes, and thymus. (B) Absence of donor-derived SpT cells in the BM and liver. (C) Generation of donor-derived CD4⁺CD8⁺ DP cells in the MLNs, but not in other lymph nodes or in the spleen after BMT.