Natural barrier against allergies discovered

Scientists of the Charité Berlin have succeeded in proving a body's own protection against allergies. They were able to show that endogenous T cells recognize harmless components of our breathing air, such as plant pollens or house dust mites, and actively suppress allergic reactions. Allergies can then arise where there are gaps in this natural barrier.

Allergies are caused by an uncontrolled or misdirected attack of the immune system against harmless components from the environment, for example, plant pollen or particles of dust mites. Until now, it was unclear whether there is an active body-own protective mechanism that specifically detects allergens and prevents the development of allergies and that may be defective in people with allergies.

Nocturnal defense against allergies discovered. (Image: BillionPhotos.com/fotolia.com)

The scientists were able to show how tolerance to most of the harmless foreign substances absorbed in the air is maintained in humans. In addition, they identified a mechanism by which certain allergens, which make up only a fraction of the inhaled foreign matter, can undermine this protection. The researchers are using a method that allows the body's own immune cells, so-called helper T cells, to be detected in the blood.

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. Until now, it has been suggested that Tregs mainly recognize endogenous components in order to protect them from attack by other cells of the immune system. When comparing allergy sufferers and healthy people, it was surprisingly found that an allergy was not as expected due to a defect of the Tregs. However, the Treg protective wall has small gaps in healthy people as well as in allergy sufferers, i. some proteins are less well recognized than others. An analysis of the allergenic (Th2) cells showed that they are directed precisely against the few unprotected proteins that deliberately undermine Treg protection.

However, it is still unclear why some patients develop an allergy to the unprotected proteins, genetic and environmental factors probably play a role here. (Source Charité)