Which part of your body is most at risk from the hazards of the outside world? According to researchers from French biology centre Inserm, the answer is your intestine, writes Martin Ince.
The intestine has the biggest area exposed to foreign agents of any part of you, about 300m2 on average, and bristles with countermeasures against the dangers they might bring. The inside of the intestine is a mucus membrane where food is digested. It has a unique population of food-processing flora whose health is essential to nutrition.
Inserm researchers at the Curie Institute in Paris have discovered a new way in which the body protects itself from infections that might enter via the intestine. Like other parts of the body, the intestine has many types of so-called T cells, which intervene against specific infections. But the French group has found a population of T cells that are present in mice, cows and humans and that have a unique and more general structure and role.
Olivier Lantz and colleagues say the cells, called mucosal-associated invariant T cells (Mait), differ because they do not have a specific set of receptors designed to respond to a particular infection.
Most T cells are geared to one potential hazard and increase in number when it is detected. But the role of Mait cells is less clearly defined.
The French team thinks that the cells exist inside the mucus of the intestine to regulate the way the intestine's immune system operates. They may have the role of managing all the other T cells in the intestine.
The team used mice to test the possible role of Mait cells. It is possible that Mait cells help the intestine to recognise and attack possible intestinal tumours and that they have a role in preventing Crohn's disease and other disorders of the intestine.
The scientists expect their work, reported in the journal Nature this week, to have medical applications soon.