Scientists at Charité Berlin have successfully demonstrated the body's own protection system against allergies. They were able to show that the body's own T cells recognize harmless components of our breathing air, such as plant pollen or dust mites, and actively suppress allergic reactions. Allergies can then arise where there are gaps in this natural protective wall.
Allergies are caused by an uncontrolled or misguided attack by the immune system against harmless constituents from the environment, for example plant pollen or particles from house dust mites. Until now it was unclear whether there is an active protective mechanism in the body that specifically recognizes allergens and prevents the development of allergies, and whether it is defective in allergy sufferers.
The scientists were able to show how tolerance is maintained in humans for the majority of harmless foreign substances taken in from the air. They also identified a mechanism by which certain allergens, which only make up a fraction of the foreign substances inhaled, can circumvent this protection. For this purpose, the researchers use a method that can be used to detect the body's own immune cells, so-called T helper cells.
Surprisingly, the researchers found almost exclusively a specialized population of T cells, the so-called regulatory T cells (Tregs). Their most important task is to actively suppress unwanted immune reactions. So far, it has been assumed that Tregs mainly recognize the body's own components, in order to protect them from attack by other cells of the immune system. When comparing allergy sufferers and healthy people, it surprisingly showed that an allergy was not due to a defect in the Tregs as expected. However, the Treg protective wall has small gaps in healthy people as well as in allergy sufferers, i.e. some proteins are less well recognized than others. An analysis of the allergy-triggering (Th2) cells showed that they are directed precisely against the few unprotected proteins that specifically circumvent Treg protection.
However, it is not yet clear why some patients develop an allergy to the unprotected proteins; genetic and environmental factors probably play a role here. (Source Charité)