Donor Tregs prevent the generation of scleroderma. (A) Lethally irradiated B6D2F1 recipients were transplanted with 5 × 10⁶ TCD BM cells with (BM+T) or without (TCD BM) 0.5 × 10⁶ CD3⁺ T cells from B6.FoxP3-DTR-GFP donor mice. (B) After transplantation, the mice were injected intraperitoneally twice a week with saline or DT from day 7 for a period of 6 weeks. (C) Representative dot plots of CD4⁺FoxP3 GFP⁺ cells gated on CD3⁺CD4⁺ T cells in spleen after saline or DT treatment at day 28. The splenic cell number and the frequency and number of CD4⁺FoxP3 GFP⁺ cells within CD3⁺CD4⁺ T cells were analyzed in (D) spleen and (E) thymus at day 28 after BMT (n = 6-9). (F) Clinical scores and survival of the recipients from the BMT as described in A (**P < .01: BM+T-saline vs BM+T-cells-DT, ***P < .001: TCD BM-saline vs TCD BM-DT, 2 experiments). (G) Representative images of H&E staining of skin samples were taken at day 28 after BMT and quantified for GVHD histopathology (n = 6-9, 2 experiments).