The 2025 Nobel Prize in Physiology or Medicine has been awarded to three pioneering scientists — Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi — for their revolutionary research that revealed how the immune system protects the body from self-destruction while defending against countless invading microbes. The trio was honored in Stockholm, Sweden, for their “fundamental discoveries relating to peripheral immune tolerance,” the Nobel Committee announced on October 6.
Discovery That Changed Immunology
The laureates’ work centers on the discovery of regulatory T cells (Tregs) — specialized immune cells that act as the body’s security guards, ensuring that the immune system does not mistakenly attack its own tissues.
- This mechanism is crucial in preventing autoimmune diseases, where the immune system targets healthy cells, leading to conditions such as lupus, rheumatoid arthritis, and multiple sclerosis.
- Their research has also paved the way for new therapeutic strategies that could lead to effective treatments for autoimmune disorders and reduced complications after organ and stem cell transplants.
How the Immune System Protects the Body
The immune system is an ‘evolutionary masterpiece’ as described by the committee. It protects the body by distinguishing harmful pathogens from normal cells and then attacking the invaders. However, some pathogens cleverly camouflage themselves by mimicking human cells, confusing the immune system and causing it to launch a misguided attack on the body’s own tissues — a hallmark of autoimmune diseases.
Sakaguchi’s Pioneering Work
Japanese immunologist Shimon Sakaguchi, now based at Osaka University, made a landmark discovery in 1995 while studying mice. His experiments revealed that the immune system, relying on a set of regulatory T cells maintain balance and prevent self-destruction. This insight provided a missing link in understanding why the immune system doesn’t attack the body more often.
Brunkow and Ramsdell’s Genetic Breakthrough
Building on Sakaguchi’s foundation, Mary E. Brunkow and Fred Ramsdell, both American researchers, made their breakthrough in the early 2000s. They discovered a mutation in a gene they named Foxp3, which showed that this gene is essential for the development and function of regulatory T cells.
Further studies revealed that mutations in the human FOXP3 gene cause IPEX syndrome, a rare but fatal autoimmune disorder in infants. In 2003, Sakaguchi confirmed that the Foxp3 gene governs the creation of regulatory T cells, linking both discoveries and cementing their collective contribution to modern immunology.
Transforming Modern Medicine
The Nobel Committee emphasized that these findings have far-reaching implications for medicine. Their discovery continues to influence research into immune regulation, tolerance, and immunotherapy across the world. The 2025 Nobel Prize in Physiology or Medicine includes a cash award of whopping 11 million Swedish kronor (approximately $1 million), shared equally amongst the three laureates.
This year’s Nobel Prize underscores the power of curiosity-driven science and collaboration across decades and continents. The discovery of regulatory T cells not only deepens humanity’s understanding of the immune system but also brings new hope for millions suffering from autoimmune and inflammatory diseases.
Helene Elliott is the senior reporter for News Raise. She covers Science news. She also has a keen interest in photojournalism. Helene holds a nomination for the prestigious Red Smith Award. She is married to author Dennis D’Agostino, a former publicist with the New York Mets.
