The 2025 Nobel Prize in Physiology or Medicine

By: Nellie Gkatzimas

Editor: Shrinidhi Sridhar

The Nobel Prize is a very honorable award given to members of  the scientific community recognizing contributions in (add fields where you can earn awards) since 1901. As of 2025, over 633 awards have been granted to 1,026 organizations and individuals. 

Of the Nobel prizes awarded in 2025 one was granted to Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi for their contributions in the Physiology or Medicine category. Their findings were revolutionary involving peripheral immune tolerance. Peripheral immune tolerance is when the immune system learns to ignore the body’s own cells and harmless substances after immune cells have left the bone marrow and thymus.

The job of the immune system is to fight infections of foreign substances that enter our body, it does this to protect our body's natural state. Unfortunately, when our immune system does not behave properly it can lead to diseases such as diabetes or lupus. These diseases occur when our immune system mistakes our body's own tissues as being an invader. For a long time scientists have believed that immune tolerance was established mostly in the thymus and bone marrow. These are the organs in which the immune cells first develop. However, recent discoveries by Brunkow, Ramsdell, and Sakaguchi have shown  that this was only part of the bigger story of the immune system.

Their research revealed that the immune system has additional safety measures and depends on peripheral tolerance, which takes place after immune cells leave the bone marrow and thymus. Sakaguchi discovered a special type of immune cell called regulatory T cells.These T cells help to keep the immune system from attacking the body. 

Sakaguchi noticed when he removed the thymus from 3-day-old mice, they encountered severe autoimmune diseases. When he gave these unhealthy mice T cells from healthy mice they recovered. Brunkow and Ramsdell were able to continue off this finding and found that one gene, FOXP3, controls how these regulatory T cells develop and function. If FOXP3 is damaged then the T cells can not work properly, and the immune system starts attacking the body, which can have detrimental consequences.

These scientists made revolutionary findings that radically changed our understanding of the immune system.We now understand that peripheral immune tolerance is not a one-time event that only happens during immune cell development. It is a continuous process maintained throughout life by specialized regulatory cells. This realization has already had impacts on the medical community in regards to treating diseases, cancer, and organ transplants. T cells have also proven helpful in treating autoimmune diseases, allowing the body to fight cancer more effectively and helping doctors achieve successful organ transplants.

The Nobel Prize in Physiology or Medicine is awarded  to those whose discoveries deepened our understanding of Physiology or Medicine, such as the discovery detailed above. These scientists were able to expand our knowledge of the immune system and opened the door to new ways of treating disease. Awards such as these are important to honor the scientists who have made amazing breakthroughs in the scientific world.  

Sources 

NobelPrize.org. (n.d.). All Nobel Prizes. Nobel Prize Outreach AB. Retrieved November 6, 2025, from https://www.nobelprize.org/prizes/lists/all-nobel-prizes/

Fernholm, A. (2025). They understood how the immune system is kept in check. Nobel Prize Outreach AB. https://www.nobelprize.org/uploads/2025/10/popular-medicineprize2025.pdf

NobelPrize.org. (2025). Scientific background: Immune tolerance. Nobel Prize Outreach AB. Retrieved November 6, 2025, from https://www.nobelprize.org/uploads/2025/10/advanced-medicineprize2025.pdf