Reconstitution of the Treg compartment after allo-BMT. (A) [BALB/c × C57BL/6]F1 recipient mice were lethally irradiated and then grafted with 3 × 10⁶ CD3ε^−/− BM cells and 3 × 10⁶ allogeneic Ly5.1⁺ C57BL/6 T cells alone (Tallo ▵) or with 3 × 10⁶ specific Thy1.1⁺ rsTreg (Tallo+rsTreg ▴). The percentage of CD4⁺FoxP3⁺ dTreg among the Ly5.1⁺CD4⁺ T cells was evaluated at days 7, 15, 30, and 60 posttransplantation. Each symbol represents the mean value and bars are the SD. For each time point, data were combined from 2 independent experiments with n = 5 to 8 mice per group. *P < .05 for Tallo vs Tallo+rsTreg. (B-C) To compare the proliferation of dTreg from Tallo group (solid line) and Tallo+rsTreg group (dashed line), mice were injected with EdU to assess T-cell division during the last 48 hours before sacrifice. (B) Histograms depict EdU incorporation in CD4⁺FoxP3⁺ dTreg, at different time points. (C) The percentage of EdU⁺ dTreg among the CD4⁺ T cells is indicated for Tallo (▵) and Tallo+rsTreg (▴) groups, at different time points. Symbols represent the mean percentage and bars are the SD. *P < .05. **P < .001. Data were cumulated from 2 independent experiments with n = 5 mice for each group. (D) [BALB/c × C57BL/6]F1 recipient mice were lethally irradiated and then grafted with 3 × 10⁶ CD3ε^−/− BM cells and 3 × 10⁶ C57BL/6 T cells from FoxP3-EGFP mice. These T cells were GFP-depleted (GFP⁻) or not (GFP^+/−) and were coinjected with 3 × 10⁶ specific rsTreg (Tallo+rsTreg) or not (Tallo). The expression of GFP among the CD4⁺ T cells was monitored at days 15, 30, and 60 posttransplantation. Dot plots are from 1 representative experiment of 2. Each experiment comprises 2 to 5 mice per group per time point. Numbers in each quadrant represent the percentage of CD4⁺GFP⁺ ± SD among the CD4⁺ T cells.