Nobel Prize 2025 in Medicine: Shimon Sakaguchi, Mary E. Brunkow, and Fred Ramsdell Honoured for Breakthrough in Immune Regulation

The Nobel Prize in Physiology or Medicine for 2025 has been awarded to Shimon Sakaguchi, Mary E. Brunkow, and Fred Ramsdell for seminal discoveries regarding how self-tolerance is established in order to prevent an immune response against oneself. Those discoveries revolutionized the understanding of immune tolerance and set the foundation for the mechanisms involved in the immunopathogenesis of autoimmune diseases, cancer, and complications in organ transplantation.

🔬 For a Pioneering Discovery in Immune Tolerance

The trio of Nobel laureates found the basis of the body's recognition of its own cells from foreign cells.

Tregs were first described in 1995 by Japanese immunologist Shimon Sakaguchi: these are specialized immune cells that inhibit harmful self-attacks.

Mary E. Brunkow and Fred Ramsdell from the United States later identified a gene known as Foxp3 that acts as the master regulator for the development and function of these regulatory T cells.

Their work showed that mutations in Foxp3 could cause severe autoimmune diseases, thus highlighting its essential role in maintaining the balance of the immune system.

📞 The Call That Never Came

During the official announcement in Stockholm, the Nobel Assembly Secretary, Thomas Perlmann, revealed that only Sakaguchi was reachable to give him the Nobel news. Brunkow and Ramsdell never picked up the phone due to, probably, the time difference on the U. S. West Coast. "He [Sakaguchi] sounded incredibly grateful and said it was a fantastic honour," Perlmann said.

👩‍🔬 The Nobel Laureates

Mary E. Brunkow

Brunkow was born in 1961, obtained her Ph. D. from Princeton University, and serves as Senior Program Manager at the Institute for Systems Biology, Seattle, where she helps to foster collaborative research endeavors in molecular biology and systems research.

Fred Ramsdell

Ramsdell was born in 1960. He gained his Ph. D. at the University of California, Los Angeles, in 1987. Presently, he works as a Scientific Advisor at Sonoma Biotherapeutics, a leading-edge biotech firm in San Francisco that develops therapies for immune-mediated diseases.

Shimon Sakaguchi

Born in 1951, Sakaguchi obtained both an M. D. in 1976 and a Ph. D. in 1983 from Kyoto University. Currently, he is a Distinguished Professor at the Immunology Frontier Research Center, Osaka University, continuing to pursue forefront research in immune regulation.

🧠 The Impact of Their Discoveries on Medicine

- 1995: Sakaguchi’s discovery of regulatory T cells changed the entire concept of immune tolerance by demonstrating that there is active regulation preventing the immune system from destroying itself.

- 2001: Brunkow and Ramsdell demonstrated that Foxp3 gene mutations cause mice and human beings to develop autoimmune disorders, including IPEX syndrome.

- 2003: Sakaguchi then went on to prove that Foxp3 functions as the master gene for regulatory T cell development; this unifies both discoveries into a common framework of immune equilibrium.

This has opened opportunities for targeted immunotherapies that can give hope to millions of patients with autoimmune conditions as well as cancer.

🏅 Details About the Nobel Prize

This prize is strictly a medicine one. It is made of a gold medal, a diploma, and cash of 11 million Swedish kronor (roughly $1.2 million). Later this year, the awards will be formally presented by the King in Stockholm.