Restoration of immune homeostasis in Tnfrsf4Cre/+R26Dta/+ mice by regulatory T cells. (a) Expansion of donor-type T cells in the blood of Tnfrsf4Cre/+R26Dta/+ (DTA host) and control Tnfrsf4Cre/+R26+/+ (WT host) recipients of purified regulatory CD45.1+CD25+CD4+ T cells. (b) Expansion and retention of FoxP3 expression in donor CD45.1+CD4+ T cells. Plots show gated CD4+ T cells from lymphoid organs of recipient mice at the end of a 10-week observation period. (c) Percentage of CD44hi(top) and CD62L-CD44hi (bottom) CD8+ T cells in the blood of the same recipients of regulatory CD25+CD4+ T cells. (d) Absolute numbers of CD44hi (top) and CD62L-CD44hi(bottom) CD8+ T cells in lymphoid organs of either DTA and WT mice that did not receive regulatory CD25+CD4+ T cells (-) or DTA and WT mice 10 weeks after transfer of CD25+CD4+ T cells (+ Treg). Values in (a-d) represent the mean (± SEM) of 7-10 mice per group pooled from three independent experiments. (e) Mean serum levels (± SEM) of IFN-γ and MCP-1 in the same mice. Similar results were obtained for IL-12p40, MIP-1α and IL-1β.