Scientists from US and Japan Recognised with the 2025 Nobel Prize for Immune System Discovery
Three scientists from the US and Japan have been awarded the 2025 Nobel Prize in Physiology or Medicine for their discovery of how the immune system controls its own activity and prevents attacks on the body.
The Nobel Assembly at Karolinska Institutet awarded the prize to Mary E. Brunkow (US), Fred Ramsdell (US), and Shimon Sakaguchi (Japan). The three laureates will share the prize money of 11 million Swedish kronor.
According to the Nobel Committee, the scientists were recognised “for their discoveries concerning peripheral immune tolerance.” This process is a key mechanism that stops the immune system from attacking healthy tissues in the body.
The laureates identified regulatory T cells (Tregs) — special immune cells that act as the body’s own safety mechanism. These cells prevent harmful immune responses that could otherwise lead to autoimmune diseases, where the immune system mistakenly targets the body’s own cells and organs.
Their findings laid the foundation for the field of peripheral immune tolerance, helping scientists understand how the immune system maintains balance. The research has also opened new possibilities for treating cancer, autoimmune diseases, and improving organ transplantation outcomes. Several potential therapies inspired by their discoveries are currently being tested in clinical trials.
“Their discoveries have been crucial for understanding how the immune system works and why most people do not develop severe autoimmune diseases,” said Olle Kämpe, Chair of the Nobel Committee.
About the Laureates:
Mary E. Brunkow, born in 1961, earned her PhD from Princeton University and is currently the Senior Programme Manager at the Institute for Systems Biology, Seattle.
Fred Ramsdell, born in 1960, completed his PhD in 1987 from the University of California, Los Angeles, and serves as Scientific Advisor at Sonoma Biotherapeutics in San Francisco.
Shimon Sakaguchi, born in 1951, received his M.D. in 1976 and Ph.D. in 1983 from Kyoto University, Japan, and is now Distinguished Professor at the Immunology Frontier Research Centre, Osaka University.
Last year, the 2024 Nobel Prize in Physiology or Medicine was awarded to Victor Ambros and Gary Ruvkun, both from the US, for their discovery of microRNA and its role in regulating gene activity. This finding has become essential for understanding how genes function in health and disease.
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