Donor-specific tolerance and reversal of insulitis in chimeric NOD recipients. (A) Chimeric NOD mice accepted donor (⬡) but rejected third-party skin grafts (—). (B) Mixed lymphocyte reaction of lymph node cell responders from chimeric recipients at 32 weeks of age against host NOD, donor FVB/N, and third-party B10A spleen cell stimulators. One representative of 3 replicate experiments is shown. (C) Chimeric NOD recipients (; n = 12) were resistant to diabetes development compared with control NOD mice without BMT (⬡; n = 26). (D) Histology of pancreata of 3-week-old NOD mice (top row), 8-week-old NOD mice before anti-CD3 treatment (middle row), and 32-week-old chimeric recipients (bottom row). The tissues from each recipient are shown in HE staining (left column), insulin staining (middle column), and 2-color staining of insulin (red), anti-CD3 mAb (green; right column). Severe lymphocyte infiltration is seen within islets of 8-week-old NOD mice, but no infiltration was observed in 3-week-old or 32-week-old chimeric recipients. One representative of 6 mice examined in each group is shown.