T cells from G-CSF-treated donors regulate aGVHD in a TGF-β-dependent fashion. (A) TGF-β was determined 7, 14, and 21 days after SCT from respective FACS-sorted CD4 (▪, n = 3), CD8 (▨, n = 3), and non-T-cell (□, n = 3) donor populations by real-time PCR, as described in “Materials and methods.” (B) Lethally irradiated B6D2F1 recipients received splenocytes from control treated B6 donors and control antibody with or without additional purified T cells from control B6 donors (control allo plus control T plus control antibody, n = 4; control allo plus control antibody, n = 4). To study the ability of T cells from G-CSF-treated B6 donors to modulate GVHD, purified T cells from G-CSF-treated donors were added to control splenocytes in the presence of anti-TGF-β or control antibody, as described in “Materials and methods” (control allo plus G-CSF T cells plus control antibody, n = 20; control allo plus G-CSF T cells plus anti-TGF-β antibody, n = 20). Survival curves by Kaplan-Meier analysis. ^*P < .02; anti-TGF-β compared with control antibody. ▴ indicates control allo plus control Ab; ▪, control allo plus control T plus control Ab; ○, control allo plus G-CSF T plus control Ab; and □, control allo plus G-CSF T plus anti-TGF-β.