08/10/2025
Nobel Prize in Medicine 2025: Decoding the Body’s Immune Balance
The 2025 Nobel Prize in Physiology or Medicine has been awarded to Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi for their groundbreaking discoveries in peripheral immune tolerance—the process by which the immune system learns to distinguish the body’s own cells from harmful invaders. Their work has transformed our understanding of autoimmune diseases and paved the way for treatments that restore immune balance.
Dr. Shimon Sakaguchi, a Japanese immunologist from Osaka University, first identified regulatory T cells (Tregs) in the 1990s and revealed their crucial role in maintaining immune tolerance. These specialized cells act as guardians, suppressing excessive immune responses and preventing the immune system from attacking the body’s own tissues. This discovery marked a major turning point in immunology and opened new possibilities for treating autoimmune and inflammatory disorders.
Building on this foundation, American scientists Dr. Mary E. Brunkow and Dr. Fred Ramsdell, then at ZymoGenetics in Seattle, discovered the FOXP3 gene, a master regulator essential for Treg development and function. They showed that mutations in FOXP3 cause severe autoimmune diseases such as IPEX syndrome, providing the first genetic proof of how immune tolerance is controlled at the molecular level.
Together, the discoveries of Sakaguchi, Brunkow, and Ramsdell have reshaped immunological science. Their work clarified why the immune system sometimes turns against itself and inspired new approaches to restore tolerance in autoimmune diseases, improve transplant success, and refine cancer immunotherapy.
This Nobel recognition celebrates a powerful collaboration between Japan and the United States—uniting molecular genetics, cellular immunology, and clinical medicine to unravel one of biology’s most complex systems. Their pioneering research stands as a lasting contribution to human health and longevity, revealing the intricate balance that keeps the immune system in harmony.
