STOCKHOLM, Oct 6, 2025 (BSS/AFP) - A US-Japanese trio on Monday won the Nobel 
Prize in Medicine for research into how the immune system is kept in check by 
identifying its "security guards", the Nobel jury said.

The discoveries by Mary E. Brunkow and Fred Ramsdell of the United States and 
Japan's Shimon Sakaguchi have been decisive for understanding how the immune 
system functions and why we do not all develop serious autoimmune diseases.

Sakaguchi, a professor at the Immunology Frontier Research Centre in Osaka, 
told Swedish broadcaster Sveriges Radio: "It's an honour for me. I'm looking 
forward to visiting Stockholm in December" to receive the award in person.

The Nobel committee was however unable to reach the two US-based laureates to 
break the news to them in person.

"If you hear this, call me," the head of the Nobel Assembly, Thomas Perlmann, 
joked at the press conference announcing the winners.

The three won the prize for research that identified the immune system's 
"security guards", called regulatory T-cells.

Their work concerns "peripheral immune tolerance" that prevents the immune 
system from harming the body, and has led to a new field of research and the 
development of potential medical treatments now being evaluated in clinical 
trials.

"The hope is to be able to treat or cure autoimmune diseases, provide more 
effective cancer treatments and prevent serious complications after stem cell 
transplants," the jury said.

- Protecting the body -

Sakaguchi made the first key discovery in 1995.

At the time, many researchers were convinced that immune tolerance only 
developed due to potentially harmful immune cells being eliminated in the 
thymus, through a process called "central tolerance".

Sakaguchi, 74, showed that the immune system is more complex and discovered a 
previously unknown class of immune cells, which protect the body from 
autoimmune diseases.

Brunkow, born in 1961 and a senior project manager at the Institute for 
Systems Biology in Seattle, and Ramsdell, a 64-year-old senior advisor at 
Sonoma Biotherapeutics in San Francisco, made the other key discovery in 
2001, when they were able to explain why certain mice were particularly 
vulnerable to autoimmune diseases.

"They had discovered that mice have a mutation in a gene that they named 
Foxp3," the jury said.

"They also showed that mutations in the human equivalent of this gene cause a 
serious autoimmune disease, IPEX." 

Two years later, Sakaguchi was able to link these discoveries.

The trio will receive their prize -- a diploma, a gold medal and $1.2 million 
split three ways -- at a formal ceremony in Stockholm on December 10.

Researchers from major US institutions typically dominate the Nobel science 
prizes, due largely to the US' longstanding investment in basic science and 
academic freedoms.

But that could change down the line following massive US budget cuts to 
science programmes announced by President Donald Trump.

Since January, the US National Institutes of Health (NIH) has terminated 
2,100 research grants totalling around $9.5 billion and $2.6 billion in 
contracts, according to an independent database called Grant Watch.

- Trump eyeing Peace Prize -

Thomas Perlmann, secretary general of the committee that awards the Nobel 
Prize for Medicine, told AFP it was "no coincidence that the US has by far 
the most Nobel laureates".

"But there is now a creeping sense of uncertainty about the US' willingness 
to maintain their leading position in research," he said.

Trump has meanwhile made no secret of the fact that he wants to win a Nobel 
himself -- the Peace Prize.

Nobel experts have however said his "America First" policies and divisive 
style give him little chance.

"It's completely unthinkable," Oeivind Stenersen, a historian who has 
conducted research and co-written a book on the prize, told AFP.

"(Trump) is in many ways the opposite of the ideals that the Nobel Prize 
represents," he said, citing "multilateral cooperation" as an example.

Trump "follows his own path, unilaterally," Stenersen added.

Sudan's networks of volunteers Emergency Response Rooms (ERR) helping people 
survive war and famine -- are seen as a possible contender this year, as are 
media watchdogs the Committee to Protect Journalists, Reporters Without 
Borders, and Yulia Navalnaya, the widow of Kremlin critic Alexei Navalny.