On October 6, the Nobel Assembly at Karolinska Institutet rewarded Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi the Nobel Prize in Physiology or Medicine 2025 for their discoveries concerning the immune system.
Their work relates to the peripheral immune tolerance, which is a system that prevents autoimmune responses in the body after immune cells mature and enter the circulation. The peripheral immune tolerance allows us to control our immune system so we can fight off all unimaginable microbes, and still avoid autoimmune diseases. In other words, the peripheral immune tolerance prevents the immune system from harming the body.
The colleagues had isolated the gene called FOXP3, which could be used as a marker for the cells. The gene controlled the development of regulatory T cells, which they identified as the immune system’s security guard. Regulatory T cells prevent the immune system from attacking its own tissues and organs. Each member played a specific role in discovering the role of regulatory T cells.
Mary Brunkow, an American molecular biologist and immunologist, currently works as a Senior Program Manager in the Hood Lab at the Institute for Systems Biology in Seattle. Born and raised in Portland, she attended St. Mary’s Academy before earning a BS in Cell Molecular Biology from the University of Washington. She went on to complete MS and Phd degrees in Molecular Biology at Princeton.
In 2001, she worked along with Fred Ramsdell at a biotech company in Seattle. They identified the specific gene FOXP3. They made this discovery while studying a strain of mice with a severe autoimmune disease and found that the mutation in the FOXP3 gene was the cause.
Fred Ramsdell is an American immunologist who is an advisor at Sonoma Biotherapeutics, a biotechnology company co-founded by him. He earned his doctorate in microbiology and immunology from the University of California, Los Angeles and holds a bachelor’s degree in biochemistry and cell biology from the University of California, San Diego.
Shimon Sakaguchi is a Japanese immunologist who works as a distinguished professor of Osaka University and a professor emeritus of Kyoto University. He graduated from the Faculty of Medicine and Graduate School of Medicine of Kyoto University, obtaining an M.D in 1976 and a PhD in 1982, where he trained as a pathologist and immunologist.
In 1995, Sakaguchi worked independently to discover the regulatory T cells that suppress the immune system’s overreactions, which were previously an unknown subtype of immune cells. His work came after his experiments revealed that the thymus (a crucial organ part of the immune system which produces white blood cells to help the body fight off infections and diseases) was not the only mechanism for preventing the immune system from attacking itself.
Their discoveries led to a new understanding of how the immune system regulates itself, thereby laying the foundation for a new field of research. Moreover, it spurred the development of new treatments for cancer and autoimmune diseases. The hope is to be able to treat or cure autoimmune diseases, provide effective cancer treatments, and prevent any serious complications after stem cell transplants.
