Absence of c-Rel in donor T cells leads to augmented Tregs in BMT recipient. Lethally irradiated BALB/c mice were transplanted with TCD-BM (ly5.1+) plus WT or c-Rel-/- T cells from B6 donors. Fourteen days after BMT, recipient spleen, liver and peripheral blood were harvested and measured for expression of CD4, CD25, Foxp3, ly5.1 and H-2Kb. Expression and percentage of CD25 and Foxp3 are shown on gated donor CD4+ cells (H2Kb+ly5.1-) of spleen, liver and peripheral blood (A, B). (C) Summary of absolute number of donor Tregs (CD4+CD25+Foxp+) in recipient spleen. Panel B and C were presented as means ± 1SD of 4 to 5 samples per group. 2 tailed student’s-t test was used for statistical analysis. *P < 0.05; **P < 0.01. n.s, no significant difference.