Note on Nobel Prize in Physiology or Medicine 2025

Note on Nobel Prize in Physiology or Medicine 2025

The Nobel Prize in Physiology or Medicine 2025 was awarded to Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi for their pioneering work on immune system regulation, particularly the discovery and genetic control of regulatory T cells (Tregs). Their research fundamentally transformed the understanding of how the immune system maintains self-tolerance and prevents autoimmune diseases.

Firstly, Shimon Sakaguchi’s discovery in the mid-1990s challenged the long-held belief that immune tolerance was ensured only in the thymus through deletion of harmful immune cells. He demonstrated the existence of a special class of immune cells—later called regulatory T cells—that actively suppress harmful immune responses in the body. This shifted immunology from a purely elimination-based model to an active regulation model.

Secondly, Brunkow and Ramsdell provided the crucial genetic explanation by identifying the Foxp3 gene, mutations of which lead to severe autoimmune conditions. Their work established that Foxp3 is essential for the development and function of regulatory T cells. This explained rare disorders such as IPEX syndrome and confirmed the central role of genetics in immune regulation.