Nobel Prize for Physiology or Medicine - 2025
The 2025 Nobel Prize for Physiology or Medicine has been awarded to Drs Mary Brunkow, Fred Ramsdell and Shimon Sakaguchi for their discovery of fundamental knowledge on how the immune system is controlled.
A properly working immune system recognises and destroy pathogens - viruses, bacteria, and fungi - without destroying your own cells. If the immune system does get out of control and targets your own cells it can cause diabetes, rheumatoid arthritis, multiple sclerosis, and other autoimmune diseases.
The cells at the heart of this story are T-cells. The thymus gland, an organ that is the middle of your upper chest, is the first way that these out-of-control T-cells are removed. If they react with human cells in the thymus they are destroyed. Dr Sakaguchi did experiments where he removed the thymus of mice just after they were born. He found that this caused the mice to develop autoimmune diseases, this made sense because without a thymus the the out of control T-cells were not removed. He then injected these same mice that did not have a thymus with blood from adult mice. The injected mice did not develop autoimmune diseases. This meant that something in the blood was able to regulate these out of control T- cells. Dr Sakaguchi was able to determine that these were a special type of T-cell called a CD25+ T-cell. These T-cells must be regulating and suppressing the out of control T-cells.
Dr Brunkow and Ramsdell’s research focused on understanding gene mutations in mice. They discovered the gene mutation of a strain of mice that suffered from autoimmune diseases. This gene was Foxp3. Mutations in the equivalent gene in humans also caused autoimmune disease.
Dr Sakaguchi then determined that the Foxp3 was involved in the development of the CD25+ T-cells. With a mutated Foxp3, the CD25+ cells didn’t develop normally and they weren’t able to destroy the out of control T-cells and autoimmune disease was the result.
Their research, that started nearly 30 years ago, is now being turned into therapies. Science takes a long time but is incredibly powerful.
Read more at the Nobel Prize website
