Nobel Prize Awarded for Discoveries in Immune Regulation
The 2025 Nobel Prize in Physiology or Medicine has been awarded to Mary Brunkow, Fred Ramsdell (both from the U.S.), and Shimon Sakaguchi (Japan) for their work revealing how the immune system distinguishes between foreign threats and healthy tissue.
Their research focused on peripheral immune tolerance and the discovery of regulatory T cells, a class of white blood cells that act as the body’s “brakes,” preventing autoimmune reactions in which the immune system attacks the body’s own cells.
Unpacking the Science
- The trio identified the gene FOXP3 as a key marker for regulatory T cells and demonstrated how this gene helps control immune responses.
- These insights have deep implications for treatment of autoimmune diseases and cancer, because manipulating immune tolerance is central to many immunotherapies.
- To date, over 200 human clinical trials are underway exploring therapeutic approaches involving regulatory T cells.
Reactions & Recognition
- Brunkow said she learned of the award when woken by her dog barking at a news photographer in Seattle.
- In Japan, Sakaguchi expressed surprise and cautious optimism about the future clinical impacts of their research.
- The Nobel Assembly at Karolinska Institute awarded the prize, which carries 11 million Swedish crowns in prize money and a gold medal.
Broader Impact
This discovery helps explain one of the great puzzles of immunology: how our immune system can be robust enough to fight infection, yet restrained enough to avoid destroying healthy tissue.
With better understanding of regulatory T cells, scientists hope to design therapies that restore balance when the immune system goes off-kilter — for instance, reducing harmful autoimmunity or improving cancer immunotherapy.
As the first Nobel in medicine for 2025, it’s set the tone for the rest of the Nobel season, as prizes in physics, chemistry, literature, peace, and economics follow in the coming days.
