The Nobel Prize in Physiology or Medicine 2025 goes to Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi, as announced by the Nobel Committee. They are honored for their pioneering work on “peripheral immune tolerance”, a control mechanism by which the body prevents the immune system from attacking its own tissues. At the core are regulatory T cells (Tregs), which act as internal moderators to dampen immune responses and avert dangerous overreactions.
Beyond the previous doctrine of exclusively “central tolerance” in the thymus, an additional protective layer exists in the body. In 1995, Sakaguchi identified Tregs as a distinct cell class. The key transcription factor is encoded by the FOXP3 gene, which effectively labels and governs Tregs. If FOXP3 is defective, immune regulation derails, and life-threatening autoimmune reactions can occur as early as infancy.
The trio’s work has fundamentally reshaped our understanding of autoimmune diseases such as type 1 diabetes, multiple sclerosis, and rheumatoid arthritis, opening new avenues for diagnostics and therapy. Clinical approaches are currently testing the administration of regulatory T cells to curb misguided immune responses and reduce transplant rejection. The honor recognizes a milestone in modern immunology: True strength of the immune system lies not in attack, but in the ability to control.
Source
1. SRF: Medizin-Nobelpreis 2025
https://www.srf.ch/wissen/nobelpreise/nobelpreis-fuer-medizin-2025-medizin-nobelpreis-geht-an-trio-zur-forschung-zum-immunsystem (accessed October 13, 2025)
(Image: Google DeepMind / Unsplash)
