The Nobel Prize in Medicine 2025 has been awarded to two American and one Japanese scientist for their groundbreaking discoveries in immunology, the Karolinska Institute announced on Monday.
Americans Mary Brunkow and Fred Ramsdell, along with Japanese scientist Shimon Sakaguchi, were recognised for their research on peripheral immune tolerance, a mechanism ensuring the immune system does not attack the body itself.
"They have identified the immune system’s guardians, the regulatory T cells," the institute explained in a statement.
Their work has been vital in understanding how the immune system functions and why severe autoimmune diseases do not develop in everyone, according to Olle Kämpe, chair of the Nobel Committee.
The discoveries by Brunkow, born in 1961, Ramsdell, aged 64, and Sakaguchi, aged 74, have laid the foundation for a new field of research and spurred the development of treatments for conditions like cancer and autoimmune diseases.
The prize money of 11 million Swedish kronor (approximately €1 million) will be evenly divided among the three laureates.
Since the inception of the Nobel Prize in Medicine in 1901, 229 individuals have received the honour, including 13 women.
The winners of the Physics and Chemistry prizes will be announced on Tuesday and Wednesday, followed by the awards for Literature and Peace. The series of announcements will conclude next Monday with the so-called Nobel Prize in Economics, funded by Sweden’s central bank.
The awards will be ceremonially presented on 10 December, commemorating the death anniversary of prize founder Alfred Nobel (1833–1896).
On 1 October, the winners of the Right Livelihood Award, often referred to as the alternative Nobel Prize, were announced in Stockholm.
