MAIT cells in autoimmunity

Abstract

Mucosal associated invariant T (MAIT) cells express a semi-invariant TCRα chain: Vα7.2-Jα33 in humans and Vα19-Jα33 in mice. They are restricted by a nonpolymorphic MHC-related molecule-1 (MR1), and cells are selected in the thymus. Interestingly, MAIT cells require B cells as well as commensal flora for their peripheral expansion. MAIT cells display antimicrobial capacity. Recently, vitamin metabolites were demonstrated as antigens created by intestinal flora for MAIT cells. MAIT cells play a protective role against autoimmune encephalomyelitis (EAE), an animal model of human multiple sclerosis (MS), wheras they play a pathogenic role in murine models of arthritis. In patients with autoimmune diseases, the frequency of MAIT cells in peripheral blood was significantly reduced. The frequency of MAIT cells reflected the disease activity in MS patients, suggesting the involvement of MAIT cells in the regulation of autoimmune diseases.