Three scientists received the Nobel Prize for discovering how our immune system worksSports and health08 October 2025, 15:45

The 2025 Nobel Prize in Physiology or Medicine was awarded to three scientists: Shimon Sakaguchi, Mary Brunkow and Fred Ramsdell. They managed to unravel how the human immune system maintains balance and does not attack its own healthy cells.

For decades, researchers have been confident that autotolerance (the immune system’s ability to avoid destroying the body’s own systems) occurs primarily in organs that produce immune cells. These are the thymus for T cells and the bone marrow for B cells.

In 1995, with the discovery of a new class of immune cells—T cells (Tregs)—scientists identified another layer of defense: peripheral tolerance. These cells work as guardians of the immune system and suppress unwanted immune responses that can cause autoimmune diseases.

Brunkow and Ramsdell discovered the molecular switch that controls T cells in 2001. They found that mutations in the FOXP3 gene caused a fatal autoimmune disease in mice. Similar mutations in humans were later shown to cause immune dysregulation and IPEX syndrome, a rare and serious autoimmune disease.

Thanks to our understanding of FOXP3 and regulatory T cells, scientists have now entered a new era in immunotherapy. The immune system is currently being used to treat autoimmune diseases and cancer. Therefore, experts are investigating ways to improve the function of Tregs to relieve rheumatoid arthritis and suppress Tregs in oncology.

Additionally, the new research may improve organ transplantation in situations where immune tolerance is critical in preventing organ rejection.