Figure 5. Mast cell-induced IL-17 enhances suppressor function of Treg cells via upregulating CD39 and CD73.

(A) The interference of IL-17 impaired the effect of mast cells on the suppressive function of Treg cells. 5×10⁶ BMMCs were injected into tumor-bearing mice by i.v. injection. IL-17 or CCL2 neutralizing antibody or Gr-1 depleting antibody was i.p. injected to the mice 1 h, 2 days and 5 days after BMMCs injection. On day 7, tumor-infiltrating Treg cells were isolated for suppression assay. (B and C) Mast cells had no effect on Treg cells expressing CTLA-4, IL-10 or TGF-β. BMMCs were injected into tumor-bearing mice. Seven days later, the tumor-infiltrating lymphocytes were isolated for the analysis of CTLA-4 by flow cytometry. The data showed the gated CD3⁺Foxp3⁺ cells. (B) or IL-10 and TGF-β by real time RT-PCR (C). (D) Mast cells upregulated the expressions of CD39 and CD73 by Treg cells. BMMCs were injected into tumor-bearing mice with IL-17 antibody or control antibody. Seven days later, the tumor-infiltrating Treg cells were isolated for the analysis of CD39 and CD73 by real time RT-PCR and western blot. (E) IL-17 had no direct effect on Treg cells. IL-17 (20 ng/ml) was added to the cultured Treg cells for 12 hours. The cells were collected for the analysis of CD39 and CD73 by real time RT-PCR. F, Blockade of adenosine signaling pathway impaired mast cell-enhanced Treg cell function. BMMCs were injected into tumor-bearing mice. BM cells were used as control. Seven days later, the tumor-infiltrating Treg cells were isolated for suppression assay in the presence or absence of adenosine receptor A_2A antagonist SCH-58261 (100 ng/ml). The data shown were the representative of 2 independent experiments in which the similar results were obtained.