The Nobel Prize 2025 in Physiology or Medicine was awarded to Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi for their groundbreaking discoveries in immunology, specifically regarding regulatory T cells that maintain immune system balance and prevent autoimmune diseases.
Understanding Immune System Security Guards
Our immune system constantly defends the body against invading microbes, many of which mimic human cells to evade detection. The central question has been how the immune system distinguishes harmful invaders from its own tissues. The laureates identified a class of immune cells known as regulatory T cells that act as the system’s security guards, suppressing immune responses that would otherwise target the body’s own organs.
Shimon Sakaguchi’s pioneering work in the 1990s revealed that immune tolerance is not solely due to the elimination of harmful cells in the thymus (central tolerance), but also involves regulatory T cells operating in the peripheral immune system. This discovery challenged existing dogma and opened new paths to understanding autoimmune disease mechanisms.
Impact on Autoimmune Disease Research
Mary Brunkow and Fred Ramsdell further elucidated the molecular and genetic mechanisms of regulatory T cells, helping explain why some individuals develop autoimmune diseases while others do not. Their work has been vital in understanding diseases where the immune system mistakenly attacks the body’s own tissues and has paved the way for novel therapeutic approaches.
Olle Kämpe, chair of the Nobel Assembly at Karolinska Institutet, stated, “Their discoveries have been decisive for our understanding of how the immune system functions and why we do not all develop serious autoimmune diseases.” This recognition highlights the crucial role of immune regulation in human health.
The 2025 Nobel Prize in Medicine underscores the importance of immune tolerance and offers hope for future treatments targeting autoimmune and inflammatory diseases worldwide.