Figure 4. Co-transfer of Dtx1^−/− tTregs with effector T cells leads to Foxp3 downregulation.

(a) DTX1 deficiency did not affect the Foxp3⁺ population when tTregs were transferred alone. We administered 1 × 10⁵ tTreg cells from WT and Dtx1^−/− mice into Rag1^−/− mice. Spleen and lymph nodes were isolated 1 week later, and the fraction of Foxp3⁺ cells in CD4⁺ T cells was determined. (b) A comparable CD4⁺ population in mice that received WT or Dtx1^−/− tTregs. Rag1^−/− mice were adoptively transferred with WT or Dtx1^−/− CD4⁺CD25⁺ tTreg cells. Spleen, peripheral lymph nodes (LNp), mesenteric lymph nodes (LNm) and colonic lamina propria (cLP) were isolated from the recipient mice a week later. Frequencies of CD4⁺ tTreg cells were analysed by flow cytometry. (c) Diminished Foxp3⁺ population from Dtx1^−/− tTregs adoptively transferred with CD4⁺CD25⁻ cells. CD4⁺CD25⁻ T cells from CD45.1⁺ mice were co-transferred with 1 × 10⁵ WT or Dtx1^−/− tTreg cells (CD45.2⁺) into Rag1^−/− mice. Spleen and lymph nodes were isolated 1 week later, and the fraction of Foxp3⁺ cells in the CD4⁺CD45.1⁻ T-cell population was determined. The percentage of Foxp3⁺ cells from spleen and lymph nodes in WT and Dtx1^−/− CD4⁺CD45.1⁻ T cells is compared from three pair of mice (right panel). ***P<0.001 (paired t-test).