Stockholm (AP) – Three scientists have won Nobel Prize in Medicine Monday for discoveries about how our immune system knows to attack bacteria rather than our own bodies.
Research by Mary E. Blankku, Dr. Fred Ramsdell and Dr. Sakaguchi revealed an important route the body uses to suppress the immune system, known as peripheral immune resistance. Experts called out important findings to understand autoimmune diseases such as type 1 diabetes, rheumatoid arthritis and lupus.
In separate projects over the years, a trio of scientists (two from the US and two from Japan) have identified the importance of what is now called regulated T cells. Scientists are currently using these findings in a variety of ways. Discover better treatments for autoimmune diseases, improve the success of organ transplants, and especially strengthen the fight against body cancer.
“Their findings were critical to understanding how our immune system works and why we don’t all develop serious autoimmune diseases,” said All Kampe, chairman of the Nobel Committee.
Blank, 64, is currently the senior program manager at the Institute of Systems Biology in Seattle. Ramsdell, 64, is a scientific advisor to San Francisco-based Sonoma Biotherapeutics. Sakaguchi, 74, is a well-known professor at the Center for Immunology Frontier Research at Osaka University, Japan.
Mary E. Blankku gets emotional after hearing that she won the Nobel Prize in Medicine on Monday, October 6, 2025 for part of her research on peripheral immune resistance in Seattle.
The first award officially known as the Nobel Prize in Physiology or Medicine 2025 Nobel Prize Announcement Presented by a panel at the Karolinska Institute in Stockholm.
Physics Award It will be announced on Tuesday. Chemistry Wednesday and literature Thursday. Nobel Peace Prize The Nobel Memorial Prize will be announced on Friday economy October 13th.
Works that won the 2025 Nobel Prize in Medicine
The immune system overlaps with ways to detect and fight bacteria, viruses, and other intruders. However, sometimes certain immune cells malpractice and accidentally attack people’s cells and tissues, causing autoimmune diseases.
Scientists once thought that the body was only regulated in a centralized manner. Major immune soldiers such as T cells are trained to find bad actors and find actors who are disappointed in ways that can cause autoimmunity in the thymus.
Nobel winner If immune cells later become confused and mistake human cells for invaders, the body has unraveled them in an additional way that suppresses the system.
Sakaguchi said, “I am interested in the mechanisms of the immune response that are supposed to protect myself, but are also responsible for and are supposed to attack.”
His experiments in mice showed that the thymic pathway was not the only explanation. In 1995 he discovered regulatory T cells, a previously unknown T cell subtype. This can also suppress hyperreactive immune cells, such as biological guards.
Then, in 2001, Blank and Ramsdell worked together at a biotechnology company investigating mice with autoimmune diseases. In a painstaking job in an era when genetic mapping was still an evolving field, I realized that certain mutations in the gene, called Foxp3, are responsible.
“It was a really small change that caused this big change from DNA levels to how the immune system works,” Brunkow told the AP.
Back in Japan, Sakaguchi “had received a lot of attention as one gene that could explain multiple autoimmune diseases, but even so, the reason why genes cause diseases was a mystery,” he said.
Two years later, Sakaguchi linked the findings to allow other hyperreactive cells to be suppressed, indicating that the FOXP3 gene regulates the development of these regulatory T cells.
Screen showing photographs of Nobel Prize-winning Mary E. Blankku, Fred Ramsdell and Sakaguchi, at the Nobel Parliament of the Karolinska Institute in Stockholm, Sweden, on Monday, October 6, 2025.
Why this work is important
The work opened up a new field in immunology, said Marie Warren Hellenius, a professor of rheumatology at the Karolinska Institute.
Dr. Jonathan Schneck, a specialist in cell immunology at Johns Hopkins University, said that until the trio’s research was published, immunologists did not understand the complexity of how to distinguish foreign cells from foreign cells.
One of the current goals is to understand how to increase the number of regulatory T cells, also known as T-Regs, to combat autoimmune diseases. It reduces the need for treatment today and instead suppresses the immune system in a way that makes patients more susceptible to infection.
The American Association of Immunologists said the recipient’s work “fundamentally shaped an understanding of immune balance.”
The discoveries have not yet led to new treatments, Schneck warned. However, it is very important to emphasize that “this work began in 1995 and is benefiting, but still offers many more benefits, but as scientists build on their work, they enjoy this work.”
How Mary E. Blankku, Fred Ramsdell and Dr. Sakaguchi responded
Nobel Committee Executive Director Thomas Perman said he had arrived at Sakaguchi via telephone Monday morning in the lab.
At a press conference a few hours later, it was interrupted by a call for congratulations from the Japanese Prime Minister, but Sakaguchi called his victory a “happy surprise.”
“There are many diseases that require further research and treatment, and we hope there will be further advances in these areas.
Meanwhile, Blankku received news of her awards from an AP photographer who came to her Seattle home early in the morning.
She said she ignored previous calls from the Nobel Committee. “My phone rang, and I looked at the number from Sweden and thought, ‘It’s just that it’s kind of spam.’ ”
“When I told Mary she won, she said, ‘Don’t be ridiculous,'” said her husband, Ross Kolcoon.
Ramsdell was not immediately able to reach the Associated Press or his employer.
Ramsdell “is one of the humblest people you’ve ever met,” Jeff Bluestone, CEO of Sonoma Biotherapeutics, told the Associated Press. “It’s great that we’re squealing his horns for him.”
The awards ceremony will be on December 10th, the anniversary of Alfred Nobel’s death. The person who founded the prize. Nobel was a wealthy Swedish industrialist and inventor of dynamite. He died in 1896.
Osaka University professor received the flowers after winning the Nobel Prize in Medicine on Monday, October 6, 2025 at a press conference in Suka, near Osaka, western Japan. (Shohei Miyano/Kyodo News via AP)
The trio shares the prize money of 11 million Swedish Croner (nearly $1.2 million).
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Wasson reported from Seattle and from Knee Guard from Washington. Contributors were Yamaguchi Mari in Tokyo, Stephanie Dazio and David Keaton in Berlin, and Adity Ramakrishnan in New York.
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AP Nobel Prize: https://apnews.com/hub/nobel-prizes
