Mice

All mice were housed under specific pathogen–free conditions in an American Association of Laboratory Animal Care–approved facility at UCSD, and all procedures were approved by the UCSD Institutional Animal Care and Use Committee. C57BLJ/6 CD45.1, CD45.2, CD45.1.2, P14 TCR transgenic (CD45.1 or CD45.1.2, both maintained on a C57BL6/J background), RAG1-deficient, and IL-10–deficient mice were bred at UCSD or purchased from the Jackson Laboratories. Mice with a loxP-flanked Zeb2 allele (35, 65) were bred with Rosa26Cre-ERT2 (ERCre) mice (66) and were maintained on a C57BL/J6 background. Rosa26Cre-ERT2–mediated deletion of the floxed Zeb2 gene was induced by oral gavage of 1 mg of tamoxifen (Cayman Chemical Company) emulsified in 100 μl of sunflower seed oil (Sigma-Aldrich) for five consecutive days and then rested for 5 days. Cells for T_reg cell suppression assays were obtained from male mice that were 12 to 28 weeks old.