Nobel 2025: Discovery that could stop your body from attacking itself

The 2025 Nobel in Medicine honours the discovery of regulatory T-cells, which are the body's immune 'security guards' that could transform treatment of autoimmune diseases and cancer

What if the secret to controlling diseases like cancer and autoimmune disorders was already inside you? The Nobel Prize in Physiology or Medicine 2025 has been awarded to three scientists, Mary E Brunkow, Fred Ramsdell, and Shimon Sakaguchi, for discovering tiny “brake cells” in the immune system that prevent it from turning against the body. Their work could open the door to groundbreaking new therapies.

 

According to the Nobel Assembly at Karolinska Institutet, this discovery could redefine how we treat diseases like diabetes, lupus, and even 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, in a statement.

 

What is the immune system, and why does it sometimes go wrong?

The immune system acts like a personal defence army. Its soldiers are the white blood cells called T-cells that patrol the body to detect and destroy harmful invaders such as viruses, bacteria, or even cancerous cells. However, sometimes these soldiers become confused and attack the body’s own healthy tissues. This is when autoimmune diseases such as type 1 diabetes, rheumatoid arthritis, or lupus occur.

What are regulatory T-cells?

Regulatory T-cells, or Tregs, are the “security guards” of the immune system. They don’t fight invaders directly, instead, they ensure the immune army doesn’t attack the wrong targets. As the Nobel Committee put it, these cells “put the brakes” on immune responses, preventing unnecessary damage. Without them, the body risks turning against itself.  ALSO READ| From muscles to immunity: Why protein is important for your health

What did the Nobel winners discover?

In the 1990s, Japanese scientist Shimon Sakaguchi proposed that special cells quietly prevented the immune system from self-destructing. His experiments in mice proved their existence.

 

“At the time, many researchers believed that immune tolerance only developed when harmful immune cells were eliminated in the thymus, through a process called central tolerance,” the Nobel Committee said. “Sakaguchi showed that the immune system is more complex and discovered a previously unknown class of immune cells that protect the body from autoimmune diseases.”

 

Later, American researchers Mary Brunkow and Fred Ramsdell discovered the FOXP3 gene, which is essential for producing regulatory T-cells. Mutations in this gene explained both a rare autoimmune disease in humans and the “scurfy” condition in mice. Together, their work revealed the genetic and cellular foundation of immune tolerance.

How does this help us in real life?

Regulatory T-cells play a crucial role in: 

• Autoimmune diseases: Defective Tregs worsen conditions like lupus, multiple sclerosis, and type 1 diabetes. 
• Organ transplants: Tregs help prevent rejection of transplanted kidneys, livers, or hearts. 
• Cancer: Sometimes, tumours exploit Tregs to silence the immune system, allowing cancer to grow unchecked. 

By learning to control Tregs, scientists can boost them to calm autoimmune attacks or suppress them to unleash the immune system against cancer.

Are new treatments coming soon?

Several clinical trials are underway exploring Treg-based therapies to improve outcomes in autoimmune diseases and organ transplants. According to the Nobel Committee, while no widely available drug exists yet, the field is advancing rapidly.

 

If these therapies succeed, they could reduce organ rejection, improve control of chronic autoimmune conditions, and even create new cancer treatments, harnessing the body’s own biology to heal itself.