The Nobel Committee at the Karolinska Institute in Stockholm has announced that the 2025 Nobel Prize in Physiology or Medicine will be jointly awarded to Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi for their groundbreaking discoveries concerning peripheral immune tolerance.

What is Peripheral Immune Tolerance?

Peripheral immune tolerance is a vital mechanism that prevents the body's immune system from attacking its own tissues, instead of targeting foreign pathogens. This balance is crucial to avoid autoimmune diseases, where the immune system mistakenly attacks the body's own cells.

Contributions of the Laureates

• Shimon Sakaguchi first identified a new class of immune cells called regulatory T cells in 1995, which act as "security guards" to calm the immune system and maintain tolerance.

• Mary Brunkow and Fred Ramsdell later discovered the genetic basis of these cells by identifying a gene called Foxp3, mutations of which cause severe autoimmune diseases. Their work demonstrated how regulatory T cells defend against autoimmune disorders and maintain immune system balance.

Impact on Medicine

Their fundamental discoveries opened new avenues for medical research, leading to the development of treatments for autoimmune diseases, improvements in cancer immunotherapy, and safer organ transplantation. Clinical trials on therapies targeting these regulatory T cells are underway, offering hope for millions worldwide.

About the Laureates

• Mary E. Brunkow, Ph.D., is a Senior Program Manager at the Institute for Systems Biology, Seattle, USA.

• Fred Ramsdell, Ph.D., is a Scientific Advisor at Sonoma Biotherapeutics, San Francisco, USA.

• Shimon Sakaguchi, M.D., Ph.D., serves as a Distinguished Professor at Osaka University, Japan.

The award ceremony will take place on December 10, 2025, to commemorate the legacy of Alfred Nobel, the founder of the Nobel Prizes.