Donor HSC engraftment across genetic barriers after TLI/ATG vs TBI. (A) A total of 10 000 KTLS-HSC from B6.luc+ mice (H2b) were infused into albino B6 (H-2b), BALB.B (H-2b), and BALB/c (H-2d) mice after myeloablative TBI (left; 950 cGy for B6, 800 cGy for BALB) or TLI/ATG (right; 17 × 240 cGy). Engraftment and the degree of donor cell expansion are indicated by bioluminescent signal intensity, showing more rapid and stronger luc+-donor cell expansion in TBI compared with TLI/ATG-conditioned recipients. Beyond 2 weeks post-HCT, images in the TBI group were oversaturated and are thus not shown. (B) Median expansion of luc+ donor B6.HSC grafts as quantified in emitted photons over total body area in congenic, miAg-mismatched, and MHC-mismatched recipients at serial time points (day +10, weeks 2, 3, 4, and 8) post-TLI/ATG and -HCT. (C) Percent donor chimerism of blood B220+ B cells (left), CD3+/TCRαβ+ T cells (middle), and CD11b+ (= Mac1+) myeloid cells (right) at 1 month post-HCT using TLI/ATG vs TBI conditioning, revealing mixed chimerism for all lineages in TLI/ATG-conditioned congenic and miAg-mismatched, but no engraftment in MHC-mismatched recipients; and full donor-chimerism in B cell and myeloid lineages after TBI conditioning but mixed chimerism for T cells. N = 5 to 7 animals per experimental group.
