Innate lymphoid cell function in the context of adaptive immunity

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.

Fig 1. ILCs, innate-like T cells, and conventional T cells are functionally compartmentalized based on tissue residency and activation pathways

ILCs, iNKT cells, γδ T cells, and T_RM cells are tissue resident populations that can rapidly produce cytokines at sites of infection. In contrast, primary conventional T cell responses take place over several days as these cells clonally expand and differentiate in secondary lymphoid organs, and then migrate to nonlymphoid tissues. ILCs are mainly activated by an array of soluble mediators, while the activation of iNKT cells, γδ T cells, and conventional T cells primarily involves direct interactions with TCR ligands presented by other cell types.