Nobel Prize in medicine: Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi awarded for immune tolerance breakthrough

The 2025 Nobel Prize in Physiology or Medicine was awarded to Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi for their pioneering research on peripheral immune tolerance, the Nobel Assembly at Karolinska Institutet said on Monday.

BREAKING NEWS The 2025 #NobelPrize in Physiology or Medicine has been awarded to Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi “for their discoveries concerning peripheral immune tolerance.” pic.twitter.com/nhjxJSoZEr

— The Nobel Prize (@NobelPrize) October 6, 2025

Sakaguchi, a Japanese scientist, first identified regulatory T cells in 1995, revealing how the immune system prevents attacks on the body’s own tissues. Brunkow and Ramsdell, both based in the United States, later identified a mutation in the Foxp3 gene linked to autoimmune disorders such as IPEX, cementing the molecular basis of immune regulation.

The trio’s work expanded understanding beyond central tolerance in the thymus, highlighting mechanisms that stop the immune system from attacking the body. Their findings have laid the groundwork for clinical applications in autoimmune disease treatment, cancer immunotherapy, and transplant rejection management.

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