Exacerbation of delayed-type hypersensitivity responses in EBV-induced gene-3 (EBI-3)-deficient mice

Epstein-Barr virus-induced gene-3 (EBI-3) associates with p28 to form interleukin-27 (IL-27) or with IL-12p35 to form IL-35. Both IL-27 and IL-35 have immunosuppressive functions and especially IL-35 has been implicated in the suppressive function of regulatory T cells (Treg). To address the role of EBI-3 in immune regulation, delayed-type hypersensitivity (DTH) responses were examined in EBI-3-deficient (EBI-3^-/-) mice. EBI-3^-/- mice developed deteriorated DTH responses as shown by the enhanced footpad swelling and augmented infiltration of inflammatory cells into the antigen-challenged footpads as compared with wild-type (WT) mice. While EBI-3-deficiency showed little effects on antigen-specific IFN-γ production of lymph node cells, IL-17 production was drastically augmented in EBI-3^-/- cells as compared with in WT cells. In addition, reduced IL-10 production was also evident in EBI-3^-/- CD4⁺ T cells. Interestingly, the development and suppressive function of Treg to inhibit effector T cell proliferation was not affected by EBI-3-deficiency. These data clearly demonstrated the immunosuppressive function of EBI-3 and provided complementary evidence that EBI-3 and EBI-3-containing cytokines might be taken into consideration as potential targets for some immune-related diseases.