a–d Kidneys from approximately 20-week-old Bach2 KO mice and their WT littermates were examined by histopathologic methods. Representative immunohistochemical images of kidney sections stained with anti-mouse IgM (upper figures) and IgG (lower figures) Abs and mean fluorescence intensities (MFIs) a, b. Scale bar, 50 μm. Representative images stained with periodic acid-Schiff and histopathologic indexes c, d. e–g Bach2 KO and WT mice were infused intravenously with normal syngeneic Foxp3+ Treg cells or PBS as a vehicle control. Foxp3+CD4+ cells among spleen cells were examined 8 weeks after infusion e. Sera were collected from the recipients at the indicated times and assayed by ELISA f. All graphs display means ± SEMs, with symbols representing the values of individual mice. Kidney sections stained with anti-IgM or anti-IgG Abs were examined by confocal fluorescence microscopy and displayed as the mean ± SEM MFI g. *p < 0.05, **p < 0.01 and ***p < 0.001 by Student’s t-test. ns, not significant.