Immunoregulatory functions of innate lymphoid cells.

Innate lymphoid cells (ILCs) are increasingly being recognized for their ability to impact both innate and adaptive immune cells in diverse contexts. ILCs have been observed in all secondary lymphoid tissues, in addition to being tissue-resident innate lymphocytes. In these locations, ILCs are poised to interact with various immune cells at different stages of an immune response. While the heterogeneity and plasticity of ILCs has complicated their study, their association with immune dysregulation in a wide range of pathologies highlights their importance to human health and disease. Notably, in addition to promoting inflammatory immune responses, populations of ILCs have been shown to inhibit immune responses through a variety of mechanisms. The reports of ILC-mediated regulation of immune responses have differed in terms of the phenotype of the regulatory ILC populations, and their mechanism of action. Yet the ability to modulate immune responses appears to be an important function of ILCs. As our understanding of this family of lymphocytes evolves, delineating the factors that dictate whether ILCs orchestrate inflammatory immune responses or suppresses these responses will be important for understanding various disease mechanisms. Here we focus on recent reports that examine how ILCs regulate immunity in different contexts.