[Role of MAIT cells in immunity against Mycobacterium tuberculosis]

Mucosal-associated invariant T cells (MAIT cells) are a class of innate immune-like T cells that are widely distributed in the human body. During infection, antigens such as vitamin B metabolites synthesized by microorganisms are presented to MAIT cells by MR1 (major histocompatibility complex class Ⅰ-like molecule), and MAIT cells are activated and exert antibacterial, antiviral, anticancer and tissue repair effects by releasing cytokines and cytotoxic molecules. Animal and in vitro studies have shown that the number of MAIT cells in the peripheral blood of patients with active tuberculosis is reduced and the cells exhibit a functional exhaustion phenotype. MAIT cells are activated by Mycobacterium tuberculosis antigens and produce inflammatory cytokines such as TNF-α, IFN-γ and cytotoxic molecules such as granzyme B to exert anti-tuberculosis effects that are MR1-dependent and cytokine-dependent. In addition, MAIT cells can also act as a bridge between innate and acquired immunity by initiating a conventional T-cell response. Currently, there are also relevant experimental studies on vaccines and drugs targeting MAIT cells, which show great potential in the prevention and control of tuberculosis. In this article, we will review the discovery and grouping, development and activation of MAIT cells, their role in Mycobacterium tuberculosis infection, and their application in tuberculosis prevention and treatment, in order to provide new immunological targets for tuberculosis prevention and treatment.