The Nobel Prize in Physiology or Medicine this year has been awarded to American researchers Mary E. Brunco and Fred Ramsdell, along with Japanese scientist Shimon Sakaguchi, for their groundbreaking work on the body’s immune system and its defense against autoimmune diseases.

The Nobel Assembly at Sweden’s Karolinska Institute announced the award on Monday, citing their discovery of regulatory T cells (Tregs), which prevent the immune system from attacking the body’s own tissues. The research has opened new possibilities for treating cancer, autoimmune diseases, and improving organ transplantation.

Sakaguchi, 74, made a key breakthrough in 1995 by showing that immune tolerance is maintained not only by eliminating harmful cells in the thymus but also by specialized immune cells that suppress self-destructive responses.

In 2001, Brunco (born 1961) and Ramsdell (64) identified mutations in the Foxp3 gene that caused severe autoimmune disorders in mice, and later linked the same mutation in humans to the rare but deadly disease IPEX syndrome.

The Nobel Committee hailed their discoveries as foundational, saying they explained why not everyone develops serious autoimmune conditions and laid the groundwork for a new field in immunology.
The laureates will receive their awards on December 10 in Stockholm, the anniversary of Alfred Nobel’s death. The prize includes a gold medal, a diploma, and USD 1.2 million in prize money.