Brunkow, Ramsdell, Sakaguchi Win 2025 Nobel for Tolerance

The 2025 Nobel Prize in Physiology or Medicine was awarded jointly to Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi by the Nobel Assembly at Karolinska Institutet for “their discoveries concerning peripheral immune tolerance.” Sakaguchi first proposed in 1995 that regulatory T cells (Tregs) actively suppress autoimmune reactions, expanding the focus beyond central thymic tolerance in the thymus. In 2001 Brunkow and Ramsdell identified mutations in the FOXP3 gene linked to severe IPEX syndrome, and subsequent work established FOXP3 as a master regulator of Treg development. Together their findings transformed immunology, spurred development of therapies for autoimmune diseases and cancer immunotherapy, and have led to multiple treatments now in clinical trials and improved transplant approaches. The three laureates — two U.S.-based scientists and a Japanese researcher — will share the 11 million Swedish krona prize and receive gold medals at the Nobel ceremony in Stockholm on December 10.