Innate lymphoid cells: new players of the mucosal immune response]

ILC have recently emerged as new subsets of innate lymphoid effectors devoid of antigen receptors and harboring strikingly diverse functions. Three main sub-types of ILC can be distinguished based on their developmental requirements and functions. ILC1 include cytotoxic natural killer cells and T-bet dependent IFN. producing cells. ILC2 are generated from bone marrow progenitors expressing GATA-3 and produce type 2 cytokines such as IL-5 and IL-13 in response to infections by parasitic worms and Influenza virus. Type 3 ILC are dependent on ROR gamma t, they are involved in the maintenance of the gut homeostasis and in the defense against intestinal pathogens. Given their close relationship with the gut and airway epithelial barriers, ILC are in the first line of defense against a number of pathogens but they also need to be tightly regulated in order to avoid chronic inflammation.