Review: Innate Lymphoid Cells: Sparking Inflammatory Rheumatic Disease?

Abstract

Immunology research is in a constant state of flux with new cell types being described on a regular basis. While most rheumatologists are familiar with the role that “T cell cytokines” such as tumor necrosis factor (TNF), interferon-g (IFNg), and interleukin-17A (IL- 17A) play in the pathogenesis of rheumatic diseases, what many may not know is that an array of innate counterparts to the conventional T cells have recently been discovered that are capable of rapidly producing these same effector cytokines. These innate counterparts include g/d T cells, invariant natural killer (iNK) cells, mucosa-associated invariant T (MAIT) cells, and innate lymphoid cells (ILCs). An insightful overview of g/d T cells, iNK cells, and MAIT cells in rheumatic disease has recently been published (1); therefore, the current review focuses on ILCs. Strikingly, some of the ILCs have only recently been discovered, in part due to their relative scarcity in peripheral blood, and their presence in numerous organs of the human body has subsequently been described. In this review, we provide the newest insights into the potential role of ILCs in the field of rheumatology and provide recommendations for future ILC research that will help to promote our understanding of rheumatic diseases even further.