Scientists Mary Brunkow, Fred Ramsdell, and Shimon Sakaguchi have been awarded the 2025 Nobel Prize in Physiology or Medicine for their groundbreaking discoveries on peripheral immune tolerance, the process by which the immune system distinguishes harmful pathogens from the body’s own tissues.
The Nobel Committee announced the award on Monday, highlighting the trio’s work as crucial for understanding autoimmune diseases.
Their research highlighted a special type of immune cell called regulatory T cells, which help keep our immune system in check so it doesn’t harm us. While Brunkow and Ramsdell conducted their research in the United States, Sakaguchi worked in Japan. Over time, their independent studies came together to reveal how the immune system maintains a healthy balance. Experts believe their findings are crucial for understanding conditions like Type 1 diabetes, rheumatoid arthritis and lupus.
Olle Kämpe, the chair of the Nobel Committee, noted, “Their findings have been decisive for understanding why most of us don’t develop serious autoimmune conditions.” This groundbreaking research is also opening new doors for medical treatments, such as improving success rates for organ transplants, enhancing cancer immunotherapies and developing innovative treatments for autoimmune diseases.
Brunkow, 64, currently serves as senior program manager at the Institute for Systems Biology in Seattle, while Ramsdell, also 64, is a scientific adviser at Sonoma Biotherapeutics in San Francisco. Sakaguchi, 74, is a distinguished professor at the Immunology Frontier Research Center at Osaka University in Japan. The Nobel Prize in Physiology or Medicine, which includes a gold medal and 11 million Swedish crowns (roughly $1.2 million), is awarded by the Karolinska Institute in Stockholm and presented by the King of Sweden.