Figure 5. IL-27 signaling in Tregs mediates Treg depletion.

(A and B) IL-27ra^–/– and C57BL6 mice were injected with B16.F10 tumor cells (2 × 10⁵/mouse) s.c. Four days later, mice were treated with AAV–IL-27 or AAV-ctrl virus i.m. at a dose of 2 × 10¹¹ DRP/mouse. Fourteen days after viral injection, mice were sacrificed and their spleens (A) and tumors (B) were analyzed for the presence of Tregs by flow cytometry. Data are expressed as mean ± SEM and represent 2 experiments with similar results. ***P < 0.001 by Student’s t test. (C) Stat1^–/– and BALB/c mice were treated with AAV–IL-27 or AAV-ctrl virus i.m. at a dose of 2 × 10¹¹ DRP/mouse. Fourteen days after treatment, mice were sacrificed, and their spleens were analyzed for the presence of Tregs by flow cytometry. Data are expressed as mean ± SEM and represent 2 experiments with similar results. ***P < 0.001 by Student’s t test. (D and E) Mixed BM chimeric mice (CD45.2⁺IL-27Rα^–/–/CD45.1⁺ C57BL/6) were injected with B16.F10 tumor cells and treated with AAV–IL-27 or AAV-ctrl vectors 4 days later. Twenty-one days after tumor cell injection, mice were sacrificed, CD45⁺ spleen cells (D) and tumor-infiltrating leukocytes (E) were analyzed for CD4/CD45.2 (left panels) and CD4/CD25/FoxP3 (right panels) by flow cytometry. Data are expressed as mean ± SEM and represent 2 experiments with similar results. *P < 0.05, **P < 0.01 by Student’s t test.