Nobel Prize 2025: Three Scientists Awarded for Findings in Peripheral Immune Tolerance

Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi Awarded $1.2 Million for their Discovery in the Medical Field

Scientists Shimon Sakaguchi, Mary E. Brunkow, and Fred Ramsdell have been awarded the Nobel Prize for their revolutionary discovery concerning “peripheral immune tolerance that prevents the immune system from harming the body.”  The award was announced by Sweden’s Karolinska Institute on Monday.

About the Ground-breaking Discovery

The Nobel-winning work by Brunkow, Ramsdell, and Sakaguchi revealed a critical mechanism of regulatory T cells that serves as the immune system's internal security force to be self-tolerant. Researchers throughout the past have believed that the body's ability to distinguish 'self' from 'non-self' was achieved by the elimination of self-reactive immune cells in the thymus, which is also known as central tolerance.

However, the trio’s collective work showed that the role of regulatory T cells in ensuring the immune system's powerful defense mechanisms doesn't turn into self-destructive forces. This discovery has established the foundation of the field of peripheral immune tolerance. Their findings are invaluable for the development of new medical treatments for conditions like autoimmune diseases, cancer immunotherapy, and organ transplants.

What is Peripheral Immune Tolerance?

Peripheral immune tolerance is an important immunological mechanism that prevents the immune system from attacking the body’s own healthy tissues. Especially the organs that are outside of the primary immune organs, such as the thymus. It is the body's secondary, yet one of the most essential defense mechanisms against autoimmunity.

Though central tolerance functions as a quality control process in the thymus, eliminating most self-reactive T cells during their maturation. A small number of these potentially harmful cells somehow escape into the bloodstream and peripheral tissues. Peripheral tolerance is the process that manages these escaped cells.

About Mary E. Brunkow, Fred Ramsdell & Shimon Sakaguchi

Scientist Mary E. Brunkow is a Ph.D. holder and Senior Program Manager at the Institute for Systems Biology. She is known for the co-discovery of the crucial Foxp3 gene. Fred Ramsdell is also a Ph.D. holder and Scientific Advisor at Sonoma Biotherapeutics; he is Brunkow’s collaborator in linking the Foxp3 gene mutation to autoimmune disorders.

Shimon Sakaguchi, on the other hand, is a distinguished professor at Osaka University with both an M.D. and a Ph.D. He pioneered the foundational discovery and initial identification of the regulatory T cells. This scientific breakthrough is bound to revolutionize the medical field, particularly the section that involves treating autoimmune diseases.