Overview

• The Nobel Assembly at Karolinska Institutet announced the award in Stockholm, the first Nobel Prize disclosure of 2025.
• Shimon Sakaguchi identified regulatory T cells in 1995, revealing a control layer beyond central tolerance in the thymus.
• Mary E. Brunkow and Fred Ramsdell reported a 2001 Foxp3 mutation explaining autoimmune-prone mice and tied the gene to severe human disease IPEX.
• By 2003, Sakaguchi showed Foxp3 governs regulatory T cell development, launching the field of peripheral tolerance with implications for autoimmunity, cancer and transplantation.
• The trio will share 11 million Swedish kronor and be honored on December 10; Brunkow is at the Institute for Systems Biology, Ramsdell advises Sonoma Biotherapeutics, and Sakaguchi is a distinguished professor at Osaka University.