STOCKHOLM: The 2025 Nobel Prize in Medicine has been announced. The award has been given to Mary E. Branco, Fred Ramsdell, and Shimon Sakaguchi for their research that provided new insights into the human immune system, particularly into peripheral immune tolerance. Shimon Sakaguchi is from Japan, while the other two laureates are from the United States.

Their research focused on some of the most fundamental questions about how the body’s immune system functions. How does our immune system work? Why doesn’t it attack our own body? Why doesn’t everyone develop autoimmune diseases? And why do only certain people get them? These are the questions that the researchers set out to answer.

Sakaguchi began this line of research in 1995, and later Branco and Ramsdell continued and completed it in 2001. Afterwards, the three scientists shared their findings with one another and reached a unified conclusion. They discovered how a special type of cell in the body, known as T cells, regulates the immune system and prevents it from attacking the body’s own cells. This breakthrough has had a major influence on the understanding, detection, and treatment of autoimmune diseases.