Tissue-Resident Innate and Innate-Like Lymphocyte Responses to Viral Infection.

Andrew Hildreth,Timothy O’Sullivan

doi:10.3390/v11030272

Abstract

Infection is restrained by the concerted activation of tissue-resident and circulating immune cells. Recent discoveries have demonstrated that tissue-resident lymphocyte subsets, comprised of innate lymphoid cells (ILCs) and unconventional T cells, have vital roles in the initiation of primary antiviral responses. Via direct and indirect mechanisms, ILCs and unconventional T cell subsets play a critical role in the ability of the immune system to mount an effective antiviral response through potent early cytokine production. In this review, we will summarize the current knowledge of tissue-resident lymphocytes during initial viral infection and evaluate their redundant or nonredundant contributions to host protection or virus-induced pathology.

Highlights

In recent years, it is becoming evident that a complete immune response requires an evolutionary division of labor between tissue-resident and circulating responses
Mucosal associated invariant T (MAIT) cells are defined by their reactivity to the major histocompatibility complexes (MHC)-I-like protein MR1, which plays a critical role in both their development and function [49]
These results suggest that the antiviral role of γδ T cells may be essential or redundant depending on the specific type of viral infection

Summary

Introduction

It is becoming evident that a complete immune response requires an evolutionary division of labor between tissue-resident and circulating responses. Innate immune cells, such as macrophages and dendritic cells (DCs), generally reside in peripheral tissues and can recognize pathogens through the expression of toll-like receptors (TLRs) to produce a wide-variety of effector molecules that can directly or indirectly limit early pathogen replication at the site of infection [1]. The recently described diversity and relative abundance of tissue-resident lymphocytes in peripheral organs suggests that early myeloid responses alone cannot efficiently restrain pathogen replication in infected tissues before initiation of antigen-specific T cell responses [2]. We will summarize the current knowledge of the direct and indirect roles of tissue-resident innate and innate-like lymphocytes in suppressing or promoting primary viral-mediated pathology in tissues

Innate Lymphoid Cells

Group 1 Innate Lymphoid Cells

Unconventional T Cells

MAIT Cells

Conclusions