Neutralization of TGF-β late after SCT attenuates chronic GVHD. Balb/c recipients underwent transplantation with 12.5 × 10⁷ splenocytes from G-CSF-treated donors, as described in “Materials and methods.” Allogeneic recipients received anti-TGF-β (□, n = 13) or control antibody (▪, n = 13) at day 14 and then 3 times per week until day 42. Control syngeneic recipients (, n = 8) were treated with control antibody. GVHD clinical scores were determined at days 14 and 42 after SCT as a measure of GVHD severity in animals, as described in “Materials and methods.” The extent of gastrointestinal, cutaneous, and hepatic GVHD was assessed by semiquantitative histopathologic examination, as described in “Materials and methods.” Data are pooled from 2 experiments and are expressed as mean ± SE. ^*P < .05, syngeneic compared with both allogeneic groups. #P < .01, allo plus anti-TGF-β compared with allo plus control antibody.