Patient Tregs express normal levels of suppression. CD4⁺CD25⁺ Tregs were immunopurified from PBMCs and assessed for their capacity to suppress the proliferation of autologous CD4⁺CD25^- cells at a responder/Treg ratio of 1:1. Percent inhibition of responder cell proliferation due to the presence of Tregs was measured using 17 samples collected from 5 cGVHD patients, 7 patients without cGVHD, and 5 healthy individuals. The solid lines represent the median values.