The Nobel Prize for 2025 in Physiology or Medicine goes to Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi “for their discoveries concerning peripheral immune tolerance,” the Royal Swedish Academy of Sciences announced in Stockholm on Monday (October 6, 2025).

The laureates identified the immune system’s security guards, regulatory T cells , which prevent immune cells from attacking our own body. “Their discoveries have been decisive for our understanding of how the immune system functions and why we do not all develop serious autoimmune diseases,” said Olle Kämpe, chair of the Nobel Committee.

In 1995 when researchers believed that immune tolerance developed through a process called ‘central tolerance’, Shimon Sakaguchi discovered a previously unknown class of immune cells, which

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