Type I IFN-based preconditioning permits HSC replacement in Sly mice. Eight-week-old Sly mice were untreated (n = 4) or treated with either 5-FU alone (n = 5) or poly(I:C) and 5-FU (n = 6), and were then given 1 × 10⁷ whole BM cells from littermate WT mice. (A) The percentage of donor-derived GUSB⁺ B cells (B220⁺), T cells (CD3ε⁺), and myeloid cells (Gr1⁺ plus CD11b⁺) in blood; or (B, C) GUSB⁺LSK (B) or CD150⁺CD48⁻ LSK (HSC) (C) in the BM 3 months after BMT (5 month of age). Horizontal bars show the average percentage for the group. Each symbol represents an individual mouse. Combined data from 6 independent experiments are shown. *P < .05; **P < .01; ***P < .001. ns, not significant.