After allograft liver transplantation, IL-22 was secreted by multiple cell sources (and possibly αβ T cells, γδ T cells, NKT cells and ILCs) stimulated by the acute injection process. Through activation of the STAT3 signaling pathway, IL-22 plays a dual role towards regulating graft survival. IL-22 may make a protective contribution at IRI in allograft liver transplantation by promoting regeneration and proliferation, anti-apoptosis and repair of injury functions for the graft. Meanwhile, persistent over-expression of IL-22 would lead to pathogenic functions for the graft at AR stage, because IL-22 can also induce the inflammatory response, increasing chemokines, recruiting inflammatory factors like Th17, and reducing Treg cells.