Nobel Prize in Physiology or Medicine

• 08 Oct 2025

On 7th October 2025, the Nobel Prize in Physiology or Medicine was awarded to Mary Brunkow, Fred Ramsdell, and Shimon Sakaguchi for their groundbreaking discoveries that revealed how the human immune system prevents itself from attacking the body it is meant to protect.

• The 2025 Nobel Prize in Physiology or Medicine recognized the trio’s discovery of the biological mechanism behind “peripheral immune tolerance,” a crucial process that keeps the immune system from damaging the body’s own tissues.
• Shimon Sakaguchi, a Japanese immunologist, made the initial breakthrough in 1995 when he identified a previously unknown class of immune cells, later termed regulatory T cells, which act as the immune system’s gatekeepers to prevent autoimmune responses.
• Before Sakaguchi’s discovery, scientists largely believed that immune tolerance occurred solely through “central tolerance,” where potentially harmful immune cells were eliminated early in their development, but his work revealed a far more intricate system of immune regulation.
• Mary Brunkow and Fred Ramsdell expanded on Sakaguchi’s findings in 2001 when they discovered that mice prone to autoimmune diseases carried a mutation in a gene they named Foxp3, which they found to be essential in maintaining immune balance.