Scientists Mary Brunkow, Fred Ramsdell and Shimon Sakaguchi have been awarded the 2025 Nobel Prize in Physiology or Medicine for "their discoveries concerning peripheral immune tolerance", the Nobel Committee announced on Monday.

The Nobel Assembly at Sweden’s Karolinska Institute selects the winners in medicine every year. Mary Brunkow, molecular biologist at the Institute for Systems Biology in Seattle, Washington, Fred Ramsdell, a scientific advisor at the firm Sonoma Biotherapeutics in Bainbridge Island, Washington and immunologist Shimon Sakaguchi at Osaka University in Suita, Japan. Each laureate receives a prize of 11 million Swedish crowns, which is about 1.2 million dollars, along with a gold medal presented by the King of Sweden.

"Their discoveries have laid the foundation for a new field of research and spurred the development of new treatments, for example, for cancer and autoimmune diseases," the Nobel Committee said in its statement.

The Nobel Prizes were established through the will of Alfred Nobel, the Swedish inventor of dynamite and a successful businessman. Since 1901, they have honoured outstanding contributions in science, literature and peace, with a few interruptions during the World Wars.

The prize in economics was introduced later and is funded by Sweden’s central bank, the Riksbank.

Winners are selected by expert committees from various institutions. All prizes are awarded in Stockholm, except for the Peace Prize, which is presented in Oslo, a tradition linked to the historical union between Sweden and Norway during Alfred Nobel’s lifetime.

Over the years, the Nobel Prize in Medicine has been awarded to some of the world’s most influential scientists. Past winners include Alexander Fleming, who received the 1945 prize for discovering penicillin. In recent years, the award has recognised breakthroughs that made the development of COVID-19 vaccines possible.

Last year’s prize went to American scientists Victor Ambros and Gary Ruvkun for discovering microRNA and explaining how it controls cell growth and development, shedding light on how cells form different types in living organisms.

The medicine prize traditionally opens the Nobel season, followed by announcements in physics, chemistry, literature, peace and economics. The Nobel awards are considered the most prestigious in their fields and continue to celebrate excellence and innovation more than a century after their inception.

The celebrations conclude with formal award ceremonies attended by the royal families of Sweden and Norway, followed by grand banquets on December 10, the anniversary of Alfred Nobel’s death.