The 2025 Nobel Prize in Physiology or Medicine has been awarded to Mary E. Branco, Fred Ramsdell, and Shimon Sakaguchi for their pioneering discovery of regulatory T cells and the mechanisms that govern the body's immune control. Their breakthrough has reshaped the field of immunology and paved the way for new therapies targeting autoimmune diseases, cancer, and complications from stem-cell transplants.

According to the Nobel Foundation's official announcement on Monday, October 6, the trio's research revealed how the immune system maintains equilibrium - distinguishing between harmful invaders and the body's own healthy cells. Their findings have redefined how scientists understand the balance between immune defense and tolerance.

Mary E. Branco, a systems biologist from Seattle; Fred Ramsdell, of Sonoma Biotherapeutics in San Francisco; and Shimon Sakaguchi, from Osaka University in Japan, were recognized for identifying regulatory T cells - the“guardians” of the immune system that prevent it from mistakenly attacking the body.

The Nobel Committee noted that earlier scientific understanding focused mainly on“central tolerance” within the immune system. However, the discovery of regulatory T cells demonstrated that immune control is far more intricate, involving multiple layers of regulation that protect against self-destructive immune responses.

Their research has already influenced medical treatment and continues to guide clinical trials aimed at improving therapies for autoimmune disorders such as multiple sclerosis, type 1 diabetes, and rheumatoid arthritis, as well as enhancing immunotherapies for cancer patients.

Global scientists and medical experts have hailed the award as one of the most important recognitions in modern medicine. The discovery, first described in the 1990s, remains vital in developing precision treatments that train the immune system to restore balance rather than suppress it.

The Nobel Committee said the collaborative work of Branco, Ramsdell, and Sakaguchi underscores how fundamental science can translate into life-changing medical progress. Their discovery deepens the world's understanding of immune regulation and opens new possibilities for treating some of humanity's most complex and debilitating diseases.

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