Facilitating cells induce regulatory T cell generation. (A) In B6 → NOD allogeneic model, NOD recipients were conditioned with 950 cGy of total body irradiation and transplanted with purified B6 HSC and NOD HSC with B6 FC via lateral tail vein injection. (B) Five weeks after transplantation, donor or recipient CD8-/CD4+/CD25+/FoxP3+ Treg in chimeric spleen were analyzed. (This research was originally published in: Huang Y, Bozulic LD, Miller T, Xu H, Hussain L-R, Ildstad ST. CD8α+ plasmacytoid precursor DC induce antigen-specific regulatory T cells that enhance HSC engraftment in vivo. Blood 2011, 17(8):2494-2505 with kind permission from The American Society of Hematology. Figure 2A has been modified.) (C) Chimeric Treg were transplanted with donor-specific B6 HSC and third-party B10.BR HSC into conditional NOD recipients. Chimeric Treg enhance HSC engraftment in an antigen-specific fashion. FC: facilitating cells; HSC: hematopoietic stem cell; Treg: regulatory T cell.