Treg cells prevent autoimmunity during infections, study shows

Recent research from the University of Chicago has revealed how certain immune cells help stop the body from attacking itself during infections. This study enhances our understanding of how the immune system works and could lead to new ways to treat autoimmune diseases. When the body faces an infection, the immune system must tell the difference between harmful germs and its own cells. If it does not, it risks damaging its own tissues. The research focuses on a specific type of immune cell called CD4+ regulatory T (Treg) cells, which play a crucial role in preventing this kind of internal attack. The study, led by Professor Pete Savage, found that Treg cells act like peacekeepers. They help to keep the immune response balanced by stopping helper T cells from attacking the body's own molecules, known as self-antigens. The research team looked into how Treg cells decide when to intervene to prevent harmful attacks from the helper T cells. They found that Treg cells are trained in the thymus to recognize self-peptides. When a foreign pathogen appears, the immune system presents these self-peptides, and the trained Treg cells intervene to prevent an autoimmune response. This ability to discriminate between self and non-self is crucial during infections. In experiments, when Treg cells specific to a certain self-peptide were removed from mice, the helper T cells attacked the body's own tissues when infected with bacteria expressing that peptide. However, these helper T cells were still able to fight off the bacterial infection. This shows that Treg cells are vital for preventing autoimmunity without hindering the immune response to actual infections. Professor Savage suggests that the typical view of how the immune system manages self and non-self recognition may be wrong. Instead of eliminating all helper T cells that react to self-antigens, having a strong population of Treg cells may be just as important for a healthy immune response. The findings indicate that maintaining a balance of Treg cells can help the body defend against infections while also preventing autoimmune diseases.