Mary Brunkow, PhD, is an American molecular biologist whose research has had a profound impact on immunology. While working at a biotechnology startup in 2001, Brunkow and colleague Fred Ramsdell identified a mutation in a gene called FOXP3, which explained the genetic basis of a severe autoimmune disorder. At the same time, Shimon Sakaguchi showed that FOXP3 governs the development of regulatory T cells—immune cells that stop the body from attacking its own healthy cells. Together, these findings created a new branch of immunology, the field of peripheral immune tolerance. This foundational work is essential for therapies targeting autoimmune disorders, transplant rejection, and inflammatory disease. For this discovery, Brunkow, Ramsdell and Sakaguchi shared the 2025 Nobel Prize in Physiology or Medicine.
