Antimicrobial activity of mucosal-associated invariant T cells

Nature immunology, Volume 11, Number 8, August 2010

Speaker: En-Hsu Chang (張許恩)                         Time: 15:00~16:00, Oct 13, 2010

Commentator: Pei- Jung Lu (呂佩融  老師)              Place: Room 601

Abstract:

There are many research about innate-like lymphocytes in recent years. Innate-like lymphocytes have features of both the innate and adaptive immune systems. Here, the authors present a group of T lymphocytes, the mucosal-associated invariant T (MAIT) cells, which have antimicrobial activity in vivo. Mucosal-associated invariant T cells (MAIT cells) are another lymphocyte subset that expresses an evolutionarily conserved invariant T cell antigen receptor (TCR) α-chain, composed of the invariant α-chain variable region 7.2 (iVα7.2) segment in humans and iVα19 in mice associated with the α-chain joining region 33 (Jα33) segment. In the previous study, it said that MAIT cells are selected on the highly phylogenetically conserved major histocompatibility complex (MHC) class I–related molecule, MR1[1].  Another research suggested that MAIT cell populations expand after birth and acquire their memory phenotype in the presence of commensal flora [2]. The MAIT cells are cells that responded in an MR1-dependent manner to antigens that presented by antigen-presenting cells (APCs). To prove the MR1-dependent manner of activation, the authors cultured E. coli with MR1⁺ APCs, and stimulated MAIT cells overnight. By using the same method, they also proved that the activation of MAIT cells was induced by a wide variety of bacteria and yeasts but not by viruses. Finally, the authors proved the antimicrobial activity of MAIT cells by intraperitoneal injecting E. coli to mice and assaying the MAIT cells mRNA expression, E. coli CFU, and T cell proliferation in spleen after 3 days. In the conclusion, the authors say that MAIT cells are evolutionarily conserved innate-like T cells with antimicrobial properties.

References:

1.      Treiner, E. et al. Selection of evolutionarily conserved mucosal-associated invariant T cells by MR1. Nature 422, 164–169 (2003).

2.      Martin, E. et al. Stepwise development of MAIT cells in mouse and human. PLoS Biol. 7, e54 (2009).