It is also a challenge for us to consider MAIT cells how to communicate with different cell types and switch with the changing cells in the context of liver diseases. tumor, MAIT cells indicate the disease progression and the outcome of therapy. In summary, MAIT cells are attractive biomarkers and restorative targets for liver disease. Keywords: alcoholic liver disease, autoimmune liver disease, liver tumor, MAIT cells, non-alcoholic liver disease 1. Intro Liver is an important immune organ and maintains the steady state of the homeostasis. Besides, it receives 75% of blood supply from your gastrointestinal tract through the portal vein, which takes on a unique part in the pathogen resistance system in the blood circulation 1. When the blood flow enters the liver, it passes through the network of innate and adaptive immune cells in hepatic sinusoid. Thus, the liver can be considered like a firewall to prevent the infection invasion into the systemic blood circulation. When infected with numerous pathogens, the liver innate cells secrete variety of cytokines, forming the first line of defense. With the progress of the diseases, the acquired immune cells perform a dominant part in anti-infectious diseases. In humans, MAIT cells are widely distributed in the body, especially in liver which constitute up to 10-50% of T cells2. MAIT cells can be triggered by riboflavin metabolites derived from microorganisms through non- polymorphic MHC class I- related (MR1) molecule on the surface of antigen showing cells (APCs) 3. Moreover, MAIT cells can be triggered by numerous inflammatory cytokines, such as IL-12, IL-18, inside a MR1-self-employed manner. Therefore, MAIT cells can be considered both non-specific immune and acquired immune cells. 2. Characteristics of MAIT cells MAIT cells communicate a semi-invariant TCR- chain (made of an invariant V7.2-J33 in human beings and V19-J33 in mice) and a limited TCR chain 4, 5. In 1993, Porcelli et al. found that CD4-CD8-T cells existed in peripheral blood of healthy Benzthiazide volunteers and selectively indicated invariant TCR chain 6. One of them called iNKT cells, which was composed of V24 and J18 gene fragments (V14 and J18 in mice). The additional one was composed of V7.2 and J33 gene fragments (V 19 and J 33 in mice). In 1999, Tilloy et al. 7 validated the constant manifestation of Benzthiazide TCR V7.2/V19-J33 resulted from a subset of particular T cells. Until 2003, Treiner et al. 4 found this fresh T cell human population originated from the intestinal mucosa, defined as the mucosal-associated invariant T cells. Once realizing the nonclassical MHC class IB molecule (MR1) offered by antigen showing cells (APCs), they could produce a variety of cytokines, including Rabbit polyclonal to IL11RA directly or indirectly in immune reactions. MAIT cells are important lymphocyte subsets, representing 0.1-10% of total T cells 2, 8, 9. The most common subset human population of MAIT cells is definitely CD8+ effector memory space phenotype. Double-negative MAIT cells (CD4-CD8-) also hold a certain proportion. However, CD4+ MAIT cells are relatively rare 10. Notably, most CD8+ MAIT cells communicate the homodimer CD8 and only a few communicate CD8 11. MAIT cells are absent in germ-free mice. The latest research explained possible mechanisms. It elucidated that vitamin B2 precursor derivatives 5-OP-RU produced by commensal bacteria came into thymus through mucosal barrier, and induced the maturation of MAIT cells through TCR transmission 12. Considering that exogenous 5-OP-RU could be captured and offered by thymic cells. It is of great significance for medical and drug study. However, MAIT cells are rare in laboratory strains of mice (C57BL/6 and Benzthiazide BALB/c). The proportion is definitely approximate to 0.6% of T cells in mice liver 13. Recently, the soluble tetramerized MR1 substances, refolded with 5-OP-RU Ag may be used to detect.