New Delhi: The 2025 Nobel Prize in Physiology or Medicine has been awarded to American scientists Mary E. Brunkow and Fred Ramsdell, along with Japanese scientist Shimon Sakaguchi, for groundbreaking work on how the immune system prevents attacks on the body’s own cells.
Announcing the award on Monday, the Nobel Assembly at Karolinska Institutet said the trio were honoured for their discoveries concerning peripheral immune tolerance, a mechanism that stops the immune system from harming the body. The prize, worth 11 million Swedish kronor, will be shared equally among the laureates.
The researchers identified regulatory T cells, the body’s immune “guards” that stop immune cells from turning against self-tissues. Their discoveries not only launched the field of peripheral tolerance but also opened avenues for therapies against cancer and autoimmune diseases, while improving prospects for organ transplantation. Several treatments inspired by their findings are currently in clinical trials.
“Their discoveries have been decisive for our understanding of how the immune system functions and why we do not all develop serious autoimmune diseases,” said Olle Kämpe, chair of the Nobel Committee.
Brunkow, born in 1961, earned a doctorate from Princeton University and is Senior Program Manager at the Institute for Systems Biology in Seattle. Ramsdell, born in 1960, received his Ph.D. in 1987 from the University of California, Los Angeles, and is Scientific Advisor at Sonoma Biotherapeutics in San Francisco. Sakaguchi, born in 1951, studied at Kyoto University and is Distinguished Professor at Osaka University’s Immunology Frontier Research Center.
Last year, the Nobel Prize in Medicine went to American scientists Victor Ambros and Gary Ruvkun for their discovery of microRNA and its role in regulating gene activity.