Phenotypic and functional characterization of FuT7^−/−-T reg cells. (A) Frequency of Foxp3⁺ T reg cells among CD4⁺ T cells in peripheral LNs and spleens of 8-wk-old WT (shaded bars) or FuT7^−/− (open bars) mice. (B) Frequency of CD4⁺Foxp3⁺ T reg cells expressing the indicated homing receptors in peripheral LNs (PLN) or spleens of WT and FuT7^−/− mice. Data in A and B are the mean and SD of values from three age-matched mice/group. Significance was measured using two-tailed, unpaired Student's t tests. *** indicates P < 0.0001; P > 0.05 for all other comparisons. (C) Proliferation of CD4⁺CD25⁻ effector T cells as measured by CFSE dilution after 96 h of culture with CD4-depleted splenocytes in the presence or absence of anti-CD3 and -CD28 antibodies (top) and the indicated ratio of WT- or FuT7^−/−-T reg cells (middle and bottom). Representative results of one out of two independent experiments.