Nobel Prize: Mary E Brunkow, Fred Ramsdell, Shimon Sakaguchi Bag The Honour In Medicine

Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi have bagged the Nobel Prize in Physiology or Medicine 2025 for their groundbreaking contributions to immunology, specifically their discoveries that explain how the body prevents its own immune system from turning against itself.

The trio's work unveiled the critical role of regulatory T cells-a specialized class of immune cells that act as internal peacekeepers, ensuring the immune system doesn't mistakenly attack healthy tissues. This process, known as peripheral immune tolerance, is essential for preventing autoimmune diseases.

"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.

Sakaguchi first challenged conventional wisdom in 1995, revealing that immune tolerance wasn't solely managed by eliminating rogue cells in the thymus-a process called central tolerance. Instead, he identified a new type of immune cell that actively suppresses harmful responses outside the thymus.
In 2001, Brunkow and Ramsdell discovered a mutation in the Foxp3 gene in mice prone to autoimmune disorders. They linked this mutation to a severe human condition called IPEX syndrome, caused by a faulty immune regulation mechanism.

Sakaguchi later connected the dots, demonstrating that Foxp3 is the master gene responsible for the development of regulatory T cells. These cells patrol the immune system, ensuring it recognizes and tolerates the body's own tissues.

Their collective discoveries have not only deepened scientific understanding of immune regulation but also opened new avenues for treating autoimmune diseases, improving cancer therapies, and enhancing organ transplant success. Several treatments inspired by their work are currently in clinical trials.