Nobel Prize in medicine goes to trio for their work on immune tolerance

Mary E. Brunkow (left), Fred Ramsdell (center) and Shimon Sakaguchi (right) won the prize for their work on the peripheral immune tolerance. — The 2025 Nobel Prize for Physiology or Medicine winners, Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi, pioneered the field of peripheral immune tolerance. (Image credit: © The Nobel Committee for Physiology or Medicine. Ill. Mattias Karlén)

A trio of researchers has won the 2025 Nobel Prize in Physiology or Medicine for discovering how the immune system is prevented from attacking our own bodies.

Mary E. Brunkow of the Institute for Systems Biology in Seattle, Fred Ramsdell of Sonoma Biotherapeutics in San Francisco, and Shimon Sakaguchi of Osaka University in Japan were awarded the prize "for their discoveries concerning peripheral immune tolerance." The Nobel Assembly at Karolinska Institutet announced the winners at a ceremony in Stockholm, Sweden, on Monday (Oct. 6).

"Their discoveries have been decisive for our understanding of how the immune system functions and why we do not all develop serious autoimmune diseases," Olle Kämpe, chair of the Nobel Committee, said in a statement.

Our immune system has to protect the body from a variety of harmful microbes, acting like a biological bodyguard. Some sneaky invaders, such as viruses, can mimic human cells, so part of the immune system's job is to determine who is on the guest list, while kicking out anything that shouldn't be there.

The new Nobel Prize winners revealed how our bodies use regulatory T cells to keep the immune system in check. Their work has launched a new field in peripheral tolerance research and led to the development of new medical treatments, including for cancer and autoimmune diseases.

Mary E. Brunkow (left), Fred Ramsdell (center) and Shimon Sakaguchi (right) were announced as Nobel laureates during a ceremony at the Karolinska Institute in Sweden on Oct. 6. (Image credit: The Nobel Committee for Physiology or Medicine)

Sakaguchi made the first key peripheral immune tolerance discovery in 1995, when many researchers thought that the immune system only developed tolerance through a process called central tolerance, during which harmful immune cells are dealt with in the thymus — a specialized organ in the chest that makes white blood cells.

However, Sakaguchi demonstrated that the immune system has additional complexities by discovering immune cells, called regulatory T cells, that suppress overactive immune responses to protect the body's cells from autoimmune diseases.

These specialist cells keep an eye on other immune cells to ensure the immune system tolerates the body's natural tissues. In other words, they prevent our biological bodyguard from getting overzealous.

RELATED STORIES

—Nobel Prize in Medicine: 1901-Present

—32 important scientists you've probably never heard of

—2 scientists snag Nobel in medicine for discovering 'microRNAs'

Brunkow and Ramsdell's contribution came six years later with their discovery that some mice had a gene mutation, named Foxp3, that makes them especially vulnerable to autoimmune diseases. The pair also found that alterations to the human version of this gene were responsible for immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, an autoimmune disease.

In 2003, Sakaguchi demonstrated that the Foxp3 gene is responsible for governing the development of regulatory T cells.

Stay tuned for more Nobel Prize announcements this week. The next announcement will be on Tuesday (Oct. 7), when we'll learn who is awarded the 2025 Nobel Prize for Physics.

TOPICS

Patrick Pester is the trending news writer at Live Science. His work has appeared on other science websites, such as BBC Science Focus and Scientific American. Patrick retrained as a journalist after spending his early career working in zoos and wildlife conservation. He was awarded the Master's Excellence Scholarship to study at Cardiff University where he completed a master's degree in international journalism. He also has a second master's degree in biodiversity, evolution and conservation in action from Middlesex University London. When he isn't writing news, Patrick investigates the sale of human remains.

You must confirm your public display name before commenting

Please logout and then login again, you will then be prompted to enter your display name.