Osaka University professor Dr. Shimon Sakaguchi receives flowers at a news conference in Suita, near Osaka, on Monday, after he won the Nobel Prize in medicine.Mizuki Sakai/The Associated Press
From insulin to the molecular machinery that regulates our genes, the subtle science of the human body has been a source of wonder – and Nobel Prizes – for more than a century.
On Monday, the Nobel Assembly at the Karolinska Institute in Sweden once again gave basic biomedical research a nod of approval by recognizing the discovery of peripheral immune tolerance, a way in which the body keeps its internal defenses from attacking its own tissues.
Three scientists – Mary E. Brunkow and Fred Ramsdell of the United States, and Shimon Sakaguchi of Japan –were awarded the 2025 Nobel Prize in Physiology or Medicine for uncovering the process, a discovery that opens the door to potential treatment for autoimmune diseases and cancer.
“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.
Mary Brunkow, Fred Ramsdell and Shimon Sakaguchi are awarded this year’s Nobel Prize in in Physiology or Medicine at Karolinska Institutet in Stockholm.Claudio Bresciani/Reuters
Dr. Sakaguchi, 74, is a professor at Osaka University’s Immunology Frontier Research Center. He was previously awarded a Canada Gairdner International Award for his discovery of regulatory T cells, also called Tregs.
In general, T cells are a key part of the immune system that neutralize infections in various ways including by producing destructive enzymes that can break down invading pathogens. But this crucial defence can become a problem when T cells become overactive and damage the body’s own cells by mistake.
While working at the Aichi Cancer Center Research Institute in Nagoya in the 1980s, Dr. Sakaguchi was able to demonstrate that a specific version of T cell produced in the thymus gland – the regulatory T cells – can suppress this effect and prevent autoimmune disease.
Mary E. Brunkow smiles after hearing about winning a Nobel Prize in medicine for part of her work on peripheral immune tolerance, in Seattle on Monday.Lindsey Wasson/The Associated Press
This work set the stage for investigations by Dr. Brunkow, 64, a senior program manager at the Institute for Systems Biology in Seattle and Dr. Ramsdell, 64, a scientific adviser for Sonoma Biotherapeutics in San Francisco. Working with mice, the two showed in 2001 that a mutation in a gene called Foxp3 derailed the system in a way that explained the rare but serious autoimmune disease in humans called IPEX.
The work has stimulated research into new treatments and ongoing clinical trials.
Earlier on Monday Dr. Sakaguchi gave a talk at a scientific conference in Chiba, Japan. Jennifer Gommerman, an immunologist at the University of Toronto who was at the talk, said if Dr. Sakaguchi knew then he had won the Nobel prize “he certainly did not let on.”
“We are all overjoyed that this prize was awarded to such an important field of immunology, and to such a great scientist,” she told The Globe and Mail.
Monday’s announcement kicks off a week of Nobel prize reveals, with the recipient or recipients of the physics prize to be named on Tuesday, chemistry on Wednesday, literature on Thursday and the Nobel Peace Prize on Friday.
The prizes were first awarded in 1901, with categories stipulated in the will of Swedish businessman and inventor Alfred Nobel.
A sixth prize for economics, added in 1969, is set to be announced on October 13.
All the prizes are bestowed annually at a special ceremony held in Stockholm on December 10, the anniversary of Alfred Nobel’s death in 1896.
With a report from the Associated Press