Overview

• Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi share the 2025 Physiology or Medicine prize for uncovering how peripheral immune tolerance prevents the body from attacking itself.
• Sakaguchi identified regulatory T cells in 1995, revealing a cell population that restrains overactive immune responses.
• In 2001, Brunkow and Ramsdell traced severe autoimmunity in scurfy mice to a Foxp3 mutation and linked FOXP3 defects in humans to the rare disease IPEX.
• By 2003, Sakaguchi showed that Foxp3 governs the development of regulatory T cells, tying the mechanism together.
• Their work launched a field now informing treatments in clinical trials for autoimmune disease, cancer and transplantation; the trio will split 11 million Swedish kronor with the prize to be presented on December 10 in Stockholm.