Donor-derived Tregs are stable and functional. (A) Demethylation status of the Foxp3 gene (TSDR) was analyzed from spleen host and donor Tregs (TCRβ⁺CD4⁺CD25⁺), isolated 7 weeks post-BMT from PGIA control and BMT-treated animals. PGIA control (N = 4) were pooled in 2 groups and BMT-treated mice (N = 5) in 3 groups (3 PGIA-induced mice, of which 2 were pooled in 1 group, and 2 nonarthritic-induced animals were pooled into 1 group) before measurement. (B) Representative carboxyfluorescein diacetate succinimidyl ester (CFSE) dilution histogram of suppressive capacity of fluorescence-activated cell-sorted host and donor Treg compared with proliferative capacity of effector T cells of healthy mice (left). Summarized suppressive capacity of host and donor Tregs after BMT at different effector T-cell:Treg ratios (1:1, 2:1, 4:1, and 8:1) (right). BMT-treated animals, N = 6 (4 PGIA-induced and 2 noninduced animals). Tregs were paired before the suppression assay. *P < .05, host vs donor (Mann-Whitney U test).