Absence of IL-27R expression on Tregs enhances reconstitution and stabilizes Foxp3 expression. (A) Lethally irradiated Balb/c recipients were transplanted with B6 Foxp3^EGFP BM (black bars, n = 5), IL-27R^−/−Foxp3^EGFP BM (light gray bars, n = 5), B6 Foxp3^EGFP BM and spleen cells (medium gray bars, n = 9), or IL-27R^−/−Foxp3^EGFP BM and spleen cells (dark gray bars, n = 9) (adjusted to yield an αβ T-cell dose of 0.7 × 10⁶ cells). The absolute number of Tregs in the spleen, liver, lung, and colon is depicted. Data are results from 2 experiments. (B) Column-purified Cell Trace Violet–labeled B6 Thy1.2⁺ T cells (1 × 10⁵) were cultured with Balb/c CD11c⁺ dendritic cells (5 × 10⁴) alone or in the presence of varying ratios of sorted CD4⁺Foxp3^EGFP+ or CD4⁺IL-27R^−/−Foxp3^EGFP+ Tregs for 5 days in triplicate wells. Control wells are depicted as black bars. Data are presented as the mean percentage ± SEM of Cell Trace Violet low expressing cells and are representative of 1 of 3 experiments with similar results. (C-E) Irradiated Balb/c mice were transplanted with B6.PL BM plus B6.PL spleen cells (0.6 × 10⁶ αβ⁺ T cells) with either 0.6 × 10⁶ CD4⁺Foxp3^EGFP Tregs or CD4⁺IL-27R^−/−Foxp3^EGFP Tregs. Representative dot plots depicting the percentage of Thy1.2⁺Foxp3⁺ Tregs in the spleen, liver, lung, and colon that retained expression of Foxp3 2 weeks posttransplantation is shown in panel C. The percentage and absolute number of CD4⁺Thy1.2⁺Foxp3⁺ T cells in the same tissue sites are depicted in panels D and E, respectively. (F-G) Irradiated Balb/c mice were transplanted with B6.PL BM and spleen cells (0.6 × 10⁶ αβ⁺ T cells) along with 0.6 × 10⁶ sorted Thy1.2⁺CD4⁺Foxp3^EGFP+ T cells. Cohorts of mice then received either an isotype control or p28 antibody on days 0 and 6. The absolute number and percentage of Thy1.2⁺CD4⁺Foxp3⁺ T cells in the spleen, liver, lung, and colon are depicted in panels F and G. Data are from 2 experiments. *P < .05, **P < .01, ***P < .001.