CNN: The 2025 Nobel Prize in physiology or medicine has been awarded to a trio of scientists – two of them American and one Japanese – for discovering how the immune system protects us from thousands of different microbes trying to invade our bodies.
Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi will share the prize “for their fundamental discoveries relating to peripheral immune tolerance,” the Nobel Committee announced Monday at a ceremony in Stockholm, Sweden.
The laureates identified “regulatory T cells,” which function like the immune system’s security guards and prevent immune cells from attacking our own body.
“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.
Sakaguchi, a Japanese immunologist, discovered a new class of T cells in 1995, the committee said, demonstrating that the immune system was more complex than commonly believed at the time.
Brunkow and Ramsdell, both American, built on Sakaguchi’s discovery in the early 2000s when they explained why a specific mouse strain was particularly vulnerable to autoimmune diseases. The pair discovered that the mice had a mutation in the gene, which they named Foxp3. They then showed that mutations in the human equivalent of this gene cause IPEX, a serious autoimmune disease.
In 2003, Sakaguchi linked their findings to his discovery in the 1990s, proving that the Foxp3 gene governs the development of the “regulatory T cells.”
The trio’s work has spearheaded research in the field of peripheral tolerance, which has helped develop treatments for cancer and autoimmune diseases, the committee said.
Thomas Perlmann, secretary of the medicine committee, said he had spoken with Sakaguchi, a professor at Osaka University, before the announcement, and that he “sounded incredibly grateful.” Due to the time difference between Sweden and the United States, Perlmann said he had not yet been able to contact Brunkow and Ramsdell.
Brunkow is a program manager at the Institute for Systems Biology in Seattle, while Ramsdell is a co-founder of Sonoma Biotherapeutics, a biotechnology firm in San Francisco.
Last year, the prize was awarded to US scientists Victor Ambros and Gary Ruvkun for their work on the discovery of microRNA, a molecule that governs how cells function in the body.
In 2023, the prize was awarded to Katalin Karikó and Drew Weissman, for their work on messenger RNA (mRNA) vaccines, a crucial tool in curtailing the spread of Covid-19.
The prize carries a cash award of 11 million Swedish kronor ($1 million).
