In October, the Nobel Committee awarded the 2025 Nobel Prize in Physiology or Medicine to Shimon Sakaguchi, Mary Brunkow and Fred Ramsdell for their discoveries in the field of autoimmunity. As has become typical for the scientific Nobel Prizes, the award-winning research is by now several decades old. But the discoveries were the basis for ongoing research into how to prevent autoimmunity that notched significant wins in 2025, in both basic research and in the clinic.