Restricting antigen expression to CD11c⁺ DCs permits BM engraftment and tolerance induction in primed recipients. (A-C) B6.SJL (CD45.1⁺) recipients were immunized (OVA/QuilA) and 2 weeks later irradiated (300 cGy) and BM (10⁷) from C57Bl/6, 11c.OVA, MII.OVA or actin.OVA (act.OVA) mice injected intravenously. At the depicted times (A) or 6 weeks later (B-C) donor leukocytes were enumerated in blood (A) or spleen (B) and lin⁻c-kit⁺ HPC enumerated in BM (C). (D-E) Memory OT-I T cells were transferred to B6.SJL mice and 1 week later mice were irradiated (300 cGy) and BM (1 × 10⁷) from non-Tg, 11c.OVA or MII.OVA mice injected intravenously. Six weeks later donor leukocytes were enumerated in spleen using flow cytometry (D) or mice were sham or OVA-challenged and OT-I cells (CD45.1⁺CD8⁺Va2⁺) in spleen enumerated (E). (F) C57Bl/6 mice were irradiated (300 cGy) and BM (10⁷) from C57Bl/6 or 11c.OVA mice injected intravenously. Four weeks later mice were double-grafted with skin from K14.mOVA mice and BALB/c allogeneic controls and graft survival monitored. Data represent mean ± SD from n = 4/group (A), individual mice pooled from a minimum of 2 experiments (B-E), or data pooled from 2 experiments (F).