Treg cells prevent autoimmune responses during infections

A new study from the University of Chicago highlights the important role of a specific type of immune cell, called Treg cells, in preventing autoimmune diseases. This research helps explain how the immune system distinguishes between harmful germs and the body's own cells. The immune system fights infections by recognizing foreign particles, called antigens, from bacteria or viruses. If it fails to differentiate these from the body's own cells, it can attack them, causing serious health issues. In this study, researchers focused on how Treg cells act as a barrier to prevent this kind of harmful attack. When the immune system encounters foreign antigens, helper T cells, known as CD4+ T cells, activate and trigger an immune response. However, when they meet self-antigens, they should remain inactive. Treg cells help manage this process by intervening when necessary to stop the helper T cells from mistakenly targeting the body's tissues. Dr. Pete Savage, a senior author of the study, explained that Treg cells serve as peacekeepers. The research team wanted to understand how these cells know when to act. They explored a concept called self-nonself discrimination, which is how the immune system tells the difference between foreign and self-antigens. Using experiments with mice, the researchers found that removing specific Treg cells led to the activation of T cells that mistakenly attacked the prostate tissue, resulting in autoimmune responses. Interestingly, the removal of these Treg cells did not affect how the T cells responded to bacterial infections. Savage pointed out that the study challenges traditional views on how the immune system avoids autoimmunity. Instead of solely eliminating T cells that react to self-antigens, having a sufficient number of matching Treg cells can equally prevent such conditions. This discovery could lead to new approaches for treating autoimmune diseases while maintaining effective responses to infections.