Targeting antigens with the CD11c promoter permits engraftment of antigen-encoding BM under immune-preserving conditions. (A-B) B6.SJL (CD45.1 congenic) mice were irradiated (1100 cGy) and BM (10⁷) from C57Bl/6 (non-Tg), 11c.OVA, MII.OVA, or actin.OVA (act.OVA) mice injected intravenously. Six weeks later engraftment was assessed in peripheral blood leukocytes (PBL) by flow cytometry (A) and mice immunized with OVA/QuilA. A further week later spleens were harvested and IFN-γ production in response to OVA_257-264 determined by ELISpot (B). (C-D) B6.SJL recipients were irradiated (200, 300, 400 cGy) and C57Bl/6 (non-Tg) BM (2 × 10⁷) transferred intravenously. At the designated time-points, PBL (C) or 6 weeks after transfer spleens (D) were analyzed by flow cytometry. (E) C57BL/6 (non-Tg) mice were irradiated, rested for 2 weeks, immunized with KLH/QuilA, and then 7 days later splenocytes prepared and IFN-γ ELISpots performed. (F-G) B6.SJL recipients were irradiated (300 cGy) and C57Bl/6 (non-Tg), 11c.OVA, MII.OVA, or actin.OVA (act.OVA) BM (10⁷) transferred intravenously. At the designated timepoints PBL (F) or 6 weeks after transfer, spleens (G) were analyzed by flow cytometry. Data are shown for individual mice pooled from 2 experiments (A-B), mean ± SD (n = 3; C), individual mice (D) from a representative experiment, mean ± SD (n = > 6 mice per group except d42, n = > 4/gp; F), or individual mice pooled from 2 (E), or 4 or more experiments (F-G). *MII.OVA @ d14 is greater than MII.OVA at d7, 28, 42, and less than 11c.OVA and non-Tg @ d14 (P < .001).