Anti-CD45RC mAb and rapamycin treatment induces tolerance in T-cell transferred Lew/BN F1 rats. (A) Control staining was realized on Lew (RT1^l), BN (RT1ⁿ) and F1 Lew/BN (RT1^l/n) PBMCs using anti-RT1^l and anti-RT1ⁿ antibodies. (B) Top, Representative staining with anti-RT1ⁿ and anti-RT1^l mAbs at different time points (days 7, 15, 22, and 50) on PBMCs of Lew/BN F1 rats injected with 2 × 10⁷ Lew T cells and treated either with anti-CD45RC mAbs or isotype control mAbs and a suboptimal dose of rapamycin. Bottom, Results are expressed in mean of percentage of RT1^n-RT1^l+ cells among PBMCs ± SEM. Three independent experiments. (C) Absolute number of cells in spleen, blood (PBMC), BM, and lymph node (LN) were analyzed in Lew/BN F1 rats, long survivor rats transferred with either Lew/BN F1 T cells or Lew T cells and treated with anti-CD45RC mAbs and rapamycin. **P < .01; ***P < .001. (D) Long survivor F1 rats (>day 120) transferred with Lew T cells and treated with anti-CD45RC mAbs and rapamycin were grafted with Lew (donor), BN (recipient), and SPD (third-party) skins. Grafts were scored daily from 0 (nonrejected graft) to 3 (rejected graft). Bonferroni posttest. *P < .05; **P < .01.