CCR5 deficiency impairs the ability of T_regs to suppress GVHD morbidity and mortality. (A) Survival of lethally irradiated B6D2 recipients of allogeneic BMT consisting of WT TCD-BM and CD25-depleted (CD25^-) T cells from WT or CCR5^-/- donors. In some groups, mice received WT TCD-BM and WT CD25^- T cells, plus T_regs from WT or CCR5^-/- donors. Figure represents data pooled from 2 separate experiments yielding similar results. For WT CD25^-,n = 10; CCR5^-/- CD25^-, n = 10; WT CD25^- plus WT T_regs, n = 8; WT CD25^- plus CCR5^-/- T_regs, n = 8. (B) Clinical GVHD scores of recipients above were evaluated at the time points shown. Data represent mean score ± SEM at each time point.