MAIT cell activation, a matter of life and death? - Phoebe Dewar

Research undertaken by Phoebe Dewar with support from Dr James Ussher, Microbiology and Immunology, School of Biomedical Sciences.
Otago Medical Research Foundation Scholar

There is the potential that signals on live bacteria are being detected by cells within the immune system, giving them permission to activate pro-inflammatory anti-bacterial cells, known as Mucosal Associated Invariant T (MAIT) cells.
Within the immune system, specific cells, called antigen presenting cells, detect the presence of bacteria via pathogen-associated molecular patterns, on/within the bacteria. Bacteria are then engulfed by the antigen presenting cell. A bacterially derived molecule is displayed on the surface of the antigen presenting cell, allowing it to tell other cells that an intruder is present. MAIT cells can recognise this bacterially derived molecule through a receptor, becoming activated and undergoing changes to its function to assist in clearing the infection from the body.
Previous experiments have shown that MAIT cell activation can be enhanced by the presence of live but not dead bacteria. In addition, antigen presenting cells can sense microbial components that are only present in live bacteria, such as bacterial RNA. Therefore, we think antigen presenting cells are communicating to the MAIT cells that bacteria are alive or dead, resulting in different levels of MAIT cell activation.
MAIT cells are one of the most abundant white blood cells in the liver and blood, so probably play a useful role within the immune system. By gaining a greater understanding of how bacteria and antigen presenting cells activate MAIT cells, we are one step closer to potentially using these cells for therapeutic means.