Ahmet Eken

By Ahmet Eken and Hamiyet Donmez‐Altuntas

Until a decade ago, natural killer (NK) cells constituted the major—if not the sole—player of innate lymphoid cell populations. The discovery of the presence and execution of curial functions by lymphoid tissue inducer‐like cells (LTi) in adults is followed by the discovery of Th2‐like innate cells and later Th1‐like helper group 1 ILCs. With these findings, the innate lymphocyte family has expanded and a new paradigm has emerged. Apparently, innate versions of helper subsets of CD4+ T cells existed in humans and mice. These cells, unlike their adaptive counterparts, lack CD3, T and B cell receptors, do not rearrange their antigen receptors and get activated by microbial products or cytokines. Furthermore, these cells rely on similar transcription factors that helper CD4+ T cells use for their development and functions (such as T‐bet, Gata3 and Rorγt); they produce similar effector cytokines (such as IFN‐γ; IL‐5, IL‐13, IL‐4; IL‐17A, IL‐22, GMCSF, respectively). Moreover, these cells assume crucial functions as an immediate, first line source of cytokines/chemokines against pathogens during protective immune responses. Lastly, very much like their adaptive counterparts, they are present and contribute to pathogenesis in various chronic inflammatory diseases of mice and humans in several tissues.

Part of the book: Lymphocyte Updates