Abstract
Innate lymphoid cells (ILCs) are a family of innate immune cells that have diverse functions during homeostasis and disease. Subsets of ILCs have phenotypes that mirror those of polarized helper T cell subsets in their expression of core transcription factors and effector cytokines. Given the similarities between these two classes of lymphocytes, it is important to understand which functions of ILCs are specialized and which are redundant with those of T cells. Here we discuss genetic mouse models that have been used to delineate the contributions of ILCs versus those of T cells and review the current understanding of the specialized in vivo functions of ILCs.