Previous studies showed that the interaction between IELs and IECs regulates the mucosal barrier integrity through the cytokines IFN-γ and IL-10 under homeostatic conditions or exogenous insults, while the dysregulated IELs plays an important role in the pathological changes in inflammatory bowel disease (IBD) or celiac disease with an increased IFN-γ and decreased IL-10. This evidence concerns the gene IFNG and inflammatory bowel disease.