2025 Nobel Prize in Physiology or Medicine

The 2025 Nobel Prize in Physiology or Medicine has been awarded to Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi. The prize was announced by the Nobel Assembly at the Karolinska Institutet in Stockholm on 6 October 2025.

The citation

The citation reads: "for their discoveries concerning peripheral immune tolerance". They share the prize equally.

The laureates

Mary E. Brunkow was born in 1961 in Portland, the United States, and is affiliated with Institute for Systems Biology, Seattle. Fred Ramsdell was born in 1960 in Elmhurst, the United States, and is affiliated with Sonoma Biotherapeutics, San Francisco. Shimon Sakaguchi was born in 1951 in Nagahama, Shiga, Japan, and is affiliated with The University of Osaka, Osaka.

Why it matters

The three scientists discovered regulatory T cells, the immune system's "security guards" that stop it attacking the body's own tissues. The work is leading to new treatments for autoimmune diseases and cancer.

The prize

The prize is worth 11 million Swedish kronor, divided between the laureates. It will be presented at a ceremony in Stockholm on 10 December, the anniversary of the death of Alfred Nobel, the Swedish inventor of dynamite whose will founded the prizes in 1895.