SA-β-gal+ LSK cells from total body–irradiated mice are highly deficient in long-term engraftment after transplantation. Five hundred CD45.2 SA-β-gal+ or SA-β-gal– LSK cells isolated from irradiated mice (TBI) or 500 control unirradiated LSK cells (CTL) along with 2 × 105 competitive CD45.1 BM cells were transplanted into lethally irradiated CD45.1 recipient. (A) Percentages of total donor-derived cells in peripheral blood at various times after transplantation. (B) Percentage of donor cell engraftment in BM 4 months after transplantation. (C) Percentages of peripheral blood T-cell, B-cell, and myeloid (M) cell engraftment at various times after transplantation. The data are presented as mean ± SD (n = 6 recipients/group). a, P < .05 vs CTL-LSK cells; b, P < .05 vs TBI-LSK β-gal– cells.