Mary E Brunkow, Fred Ramsdell and Shimon Sakaguchi have won the Nobel Prize in Medicine for their discoveries concerning peripheral immune tolerance.
Ms Brunkow is a senior programme manager at the Institute for Systems Biology in Seattle.
Mr Ramsdell is a scientific adviser for Sonoma Biotherapeutics in San Francisco.
Mary Brunkow, Fred Ramsdell and Shimon Sakaguchi have been awarded the 2025 Nobel Prize in Physiology or Medicine for their groundbreaking discoveries concerning peripheral immune tolerance that prevents the immune system from harming the body.
The Nobel Prize laureates… pic.twitter.com/h2yVHYSbxH— The Nobel Prize (@NobelPrize) October 6, 2025
Mr Sakaguchi is a distinguished professor at the Immunology Frontier Research Centre at Osaka University in Japan.
Thomas Perlmann, secretary-general of the Nobel Committee, said he was only able to reach Mr Sakaguchi by phone on Monday morning, and he left voicemails for Ms Brunkow and Mr Ramsdell.
Peripheral immune tolerance is one way the body helps keep the immune system from getting out of whack and attacking your own tissues instead of foreign invaders.
The award is the first of the 2025 Nobel Prize announcements and was announced by a panel at the Karolinska Institute in Stockholm.
Last year’s prize was shared by Americans Victor Ambros and Gary Ruvkun for their discovery of microRNA, tiny bits of genetic material that serve as on and off switches inside cells that help control what the cells do and when they do it.
Nobel announcements continue with the physics prize on Tuesday, chemistry on Wednesday and literature on Thursday.
The Nobel Peace Prize will be announced on Friday and the Nobel Memorial Prize in economics on October 13.
Our immune system is an evolutionary masterpiece. Every day it protects us from the thousands of different viruses, bacteria and other microbes that attempt to invade our bodies. Without a functioning immune system, we would not survive.
One of the immune system’s marvels is its… pic.twitter.com/TzBWuIrTgn— The Nobel Prize (@NobelPrize) October 6, 2025
The award ceremony will be held on December 10, the anniversary of the death of Alfred Nobel, who founded the prizes.
Nobel was a wealthy Swedish industrialist and the inventor of dynamite.
He died in 1896.
The trio will share the prize money of 11 million Swedish kronor (£870,000).
