The Nobel Prize in Physiology or Medicine 2025 has been awarded for discoveries that explain how the immune system attacks hostile infections, but not the body's own cells.
The prize is shared by Japan's Shimon Sakaguchi and US researchers Mary Brunkow and Fred Ramsdell.
They discovered "security guards" that eliminate parts of the immune system that could attack the body.
Their work is being used to develop new treatments for autoimmune diseases and cancer.
The winners share a prize fund worth 11m Swedish kronor (£870,000).
