IFN‐γ is mainly produced by innate lymphoid cells (ILCs) – a heterogeneous group of cytokine‐producing lymphocytes that is predominantly located at mucosal barrier surfaces, such as the IEB.[76] The proximity of ILCs to the IEB enables them to sense microbial endotoxin or tissue damage at an early stage and to produce IFN‐γ to recruit other innate immune cells, such as MNPs.[38, 77, 78] IFN‐γ is also an important cytokine for immune responses by CD4+ cells[76] and has been shown to drive excessive immune responses against microbial components within the apical content in IBD.[77]. This evidence concerns the gene IFNG and inflammatory bowel disease.