Nobel Prize 2025 Awarded for Immune System Discovery

The 2025 Nobel Prize in Physiology or Medicine was awarded to Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi. Their work revealed how the immune system decides what to attack and what to protect. This discovery focuses on regulatory T cells that prevent the immune system from harming the body itself. The announcement was made at the Karolinska Institutet in Stockholm on October 6, 2025.

Peripheral Immune Tolerance and Its Importance

Peripheral immune tolerance is a mechanism that stops the immune system from attacking the body’s own tissues. It operates outside the brain and spinal cord, in the peripheral immune system. This process is crucial to prevent autoimmune diseases where the immune system mistakenly targets the host.

Discovery of Regulatory T Cells (Treg Cells)

Shimon Sakaguchi first identified regulatory T cells in 1995. Unlike other T cells that attack pathogens, Treg cells suppress immune responses. This calming effect protects the body from self-inflicted damage. Sakaguchi’s research began in 1979, culminating in this breakthrough that reshaped immunology.

Role of T Cells in Immune Defence

T cells are white blood cells that defend the body against infections. They have different types, each with specific functions identified by surface proteins. Regulatory T cells act as moderators, ensuring that immune attacks do not damage healthy tissues.

Contributions of Mary Brunkow and Fred Ramsdell

Brunkow and Ramsdell studied a rare autoimmune condition in male scurfy mice. These mice suffered tissue destruction due to faulty T cell regulation. Their research pinpointed mutations affecting Treg cells, providing insight into autoimmune disease development. Both conducted this work while at Celltech Chiroscience in Washington.

Global Impact of the Discovery

About Treg cells has vast implications for treating autoimmune diseases, allergies, and transplant rejection. It also opens pathways for new therapies that can modulate immune responses safely. The Nobel Prize marks the importance of basic research in improving human health.

Scientific Background of the Laureates

Shimon Sakaguchi earned his medical degree from Kyoto University and currently works at Osaka University. Mary Brunkow holds a PhD from Princeton University and is a senior program manager at the Institute for Systems Biology. Fred Ramsdell has a PhD from UCLA and serves as a scientific advisor at Sonoma Biotherapeutics.