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).”Their discoveries have been decisive for our understanding of how the immune system functions and why we do not all develop serious autoimmune diseases,” says Olle Kämpe, chair of the Nobel Committee.The trio’s research is critical to understanding how the immune system works – how does it protect us from thousands of different infections that are trying to invade the body? But, at the same time, leaves our own tissues unscathed?Our immune system uses white blood cells that look for signs of infection – even viruses and bacteria that it has never met before.The cells use sensors – called receptors – that are made randomly in a quadrillion different combinations.This gives the immune systems the capability to attack a wide variety of invaders, but the randomness of the process inevitably makes white blood cells that can attack our body.Scientists already knew that some of these problematic white blood cells were destroyed in the thymus – where white blood cells mature.The Nobel prize this year goes t …
