Immune cells go to school to learn to fight infections

A team of local researchers have discovered that a large portion of our immune cells need to go to school to learn how to fight off infections.

Mucosal-associated invariant T cells (MAIT cells) have long been a mystery to scientists. It was known that they made up a large portion of the human body’s immune cells, but their exact function and processes was undetermined.

Collaborating with colleagues from the University of Queensland, researchers from Monash University and the University of Melbourne found that the MAIT cells have a three-stage intrathymic development pathway that mirrors the trajectory of a tertiary education in humans.

MAIT cells detect indications of infection by sniffing out microbial vitamin B2 derivatives produced by bacteria. Although these key infection-fighting cells are a substantial percentage of our overall immune system, their exact purpose had not previously been identified.

Working out of the Peter Doherty Institute for Infection and Immunity, a joint venture between Royal Melbourne Hospital and the University of Melbourne, the research team discovered that MAIT cells have three distinct developmental stages.

“The logical step was to look at how these cells are produced and we found that the three developmental stages are like primary school, high school and university,” said PhD student Hui-Fern Koay, one of the paper’s authors.

MAIT cells develop alongside other immune cells in the thymus before moving around the body to fulfil their infection-fighting duties.

“Just like real students, the very early cells don’t do very much,” said immunologist and co-leader of the research team Dr Daniel Pellici, “but we identified some of the important factors that help them to mature. It seems that the younger ones’ sole purpose is to get an education so that later on they can do the important job of fighting infection.”

According to co-lead Professor Dale Godfrey: “This developmental map that we have defined lays the foundations to truly understand MAIT cells; what controls their production, numbers and function; and how to manipulate their numbers to improve immunity to infections and other diseases.”

The paper ‘A three-stage intrathymic development pathway for the mucosal-associated invariant T cell lineage’ is published in Nature Immunology 2.