In a landmark recognition of immunological science, the 2025 Nobel Prize in Physiology or Medicine has been awarded jointly to Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi for their revolutionary discoveries on how the human immune system maintains self-control, preventing it from turning against the body’s own organs.
BREAKING NEWS
The 2025 #NobelPrize in Physiology or Medicine has been awarded to Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi “for their discoveries concerning peripheral immune tolerance.” pic.twitter.com/nhjxJSoZEr— The Nobel Prize (@NobelPrize) October 6, 2025
Their work, which unraveled the mysteries of peripheral immune tolerance, has transformed modern understanding of autoimmune disorders and paved the way for new treatments targeting diseases such as type 1 diabetes, multiple sclerosis, and rheumatoid arthritis.
The trio’s research illuminated the crucial role of regulatory T cells (Tregs), a specialized subset of immune cells that act as peacekeepers within the immune system. These cells ensure that while the body mounts fierce attacks on invading microbes, it spares its own healthy tissues from destruction.
Before their discoveries, scientists struggled to explain how the immune system distinguished between harmful pathogens and the body’s own cells, given that many microbes mimic human molecular patterns to escape detection. Brunkow, Ramsdell, and Sakaguchi’s groundbreaking studies closed this gap, revealing the genetic and molecular pathways that underpin immune tolerance.
Their findings not only deepened scientific insight into immune balance but also reshaped therapeutic approaches, leading to experimental treatments that harness or restore regulatory T cells to combat autoimmune and inflammatory diseases.
The Laureates Behind the Discovery
Mary E. Brunkow (born 1961) completed her Ph.D. at Princeton University and now serves as Senior Program Manager at the Institute for Systems Biology in Seattle. Her work helped identify the molecular markers that define regulatory T cells and their role in maintaining immune equilibrium.
Fred Ramsdell (born 1960) earned his Ph.D. in 1987 from the University of California, Los Angeles, and is currently Scientific Advisor at Sonoma Biotherapeutics, San Francisco. Ramsdell’s research has focused on the genetic basis of immune regulation and its implications for developing next-generation immunotherapies.
Shimon Sakaguchi (born 1951), widely regarded as a pioneer in immunology, obtained his M.D. in 1976 and Ph.D. in 1983 from Kyoto University, Japan. Now a Distinguished Professor at the Immunology Frontier Research Center, Osaka University, Sakaguchi first identified the existence of regulatory T cells in the 1990s, a discovery that laid the foundation for the field of immune tolerance.
The Nobel Assembly hailed the laureates’ work as a turning point in biomedical science, noting that their discoveries “unlocked the mechanisms of immune self-restraint, revealing how the body achieves balance between defense and destruction.”
