BACH2 is repurposed following Treg lineage commitment and is not required for maintenance of Foxp3 expression or repression of helper cytokines. (A) Representative flow cytometry plots showing Rosa26^flSTOP-tdRFP induction in CD4⁻ CD8⁻ lymphocytes and CD8⁺ or CD4⁺ T cells from Bach2^fl/flFoxp3^{EGFP-Cre-ERT2}Rosa26^flSTOP-tdRFP mice administered tamoxifen for 8 wk. (B) Quantitation of relative Bach2 excised allele abundance in FACS-purified CD4⁺ Foxp3⁻ Tconv and CD4⁺ Foxp3⁺ Treg cells isolated from the spleens of animals of indicated genotypes administered tamoxifen for 8 wk. (C) Representative flow cytometry (left) and replicate measurements (right) of the frequency of EGFP⁻ (ex-Treg) cells within RFP⁺ CD4SP thymocytes or CD4⁺ splenocytes of mice of indicated genotypes fed tamoxifen for 8 wk. Data show seven mice per genotype. (D) Frequency of IFN-γ⁺ Treg cells isolated from spleens of Bach2^+/+Foxp3^{EGFP-Cre-ERT2} mice (Bach2^+/+) and Bach2^fl/flFoxp3^{EGFP-Cre-ERT2} mice (Bach2^fl/fl) given tamoxifen feed for 8 wk. Data show seven mice per genotype. (A–D) Data are representative of two independently repeated experiments. ns, not significant; unpaired two-tailed Student’s t test (C and D). Numbers in gates show percentages. Bars and error show mean and SEM.