CD8⁺FoxP3⁺ T_reg are expanded after administration of RAPA and IL-2 Ab complexes after BMT. (A) Recipient B6D2F1 mice were lethally irradiated and 24 hours later transplanted with BM and T cells from B6.FoxP3-GFP mice. Recipients received RAPA daily (1.5 mg/kg intraperitoneally) and/or IL-2 Ab complexes at day 0 and day 4 after transplantation in the combinations shown. At day 7, mLN were removed and analyzed for CD8⁺FoxP3⁺ T_reg conversion. Representative plots are shown for graphs in the lower panel displaying combined data from 2 duplicate experiments; n = 8 per group. **P < .01. ***P < .005. B6D2F1 recipients were lethally irradiated and received BM and T cells from B6.WT donors combined with sorted CD8⁺ T cells from either (B) FoxP3.LuciDTR-4 donors (luciferase, GFP, and the DT receptor-driven of the FoxP3 promoter, labeled as B6.FoxP3-luc⁺; n = 8 per group) or (C) B6.β-actin-luc⁺ (n = 3 or 4 per group) mice 24 hours later. RAPA and IL-2 Ab complex was administered as in panel A. At day 7, recipients were killed 5 minutes after luciferin injection, and spleen, inguinal LN, liver, thymus, lung, and gut removed and imaged individually. Representative images from 2 duplicate experiments are shown with bioluminescence imaging quantitated and shown as mean ± SEM. *P < .05. **P < .01. (D) Recipients were transplanted as in panel B with only the CD8⁺ component from B6.FoxP3-luc⁺ donors and imaged weekly from day 12. Images are shown with graph displaying mean ± SEM. **P < .01, saline versus RAPA + IL-2 Ab complexes at each time point.