Activation and Function of iNKT and MAIT Cells

摘要

Over the last two decades, it has been established that pepndes are not The only antigens recognized by T lymphocytes. Here, we review information on two T lymphocyte populations that recognize nonpeptide antigens: invariant natural killer T cells (iNKT cells), which respond to glycolipids, and mucosal associated invariant T cells (MAIT cells), which recognize microbial metabolites. These two populations have a number of striking properties that distinguish them from the majority of T cells. First, their cognate antigens are presented by nonclassicai class I antigen-presenting molecules; CD1 d for iNKT cells and MR1 for MAIT cells. Second, these T lymphocyte populations have a highly restricted diversity of their T cell antigen receptor a chains. Third, these cells respond rapidly to antigen or cytokine stimulation by producing copious amounts of cytokines, such as IFNy, which normally are only made by highly differentiated effector T lymphocytes. Because of their response characteristics, iNKT and MAIT cells act at the interface of innate and adaptive immunity, participating in both types of responses. In this review, we will compare these two subsets of innate-like T cells, with an emphasis on the various ways that lead to their activation and their participation in antimicrobial responses.