A trio of researchers has won the 2025 Nobel Prize in Physiology or Medicine for discovering how the immune system is prevented from attacking our own bodies.

Mary E. Brunkow of the Institute for Systems Biology in Seattle, Fred Ramsdell of Sonoma Biotherapeutics in San Francisco, and Shimon Sakaguchi of Osaka University in Japan were awarded the prize "for their discoveries concerning peripheral immune tolerance." The Nobel Assembly at Karolinska Institutet announced the winners at a ceremony in Stockholm, Sweden, on Monday (Oct. 6).

The three scientists' research, honored with the 116th medicine prize, provides insights into keeping the immune system under control to fight microbes and avoid 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," Olle Kämpe, chair of the Nobel Committee, said in a statement.