Nobel Prize in Physiology or Medicine 2025: How our bodies prevent the immune system from mistakenly attacking itself

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The Immune System's Guardians: Meet the 2025 Nobel Laureates

Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi: Discoverer of how our bodies prevent the immune system from mistakenly attacking itself.
Credit: Nobel

The 2025 Nobel Prize in Physiology or Medicine has been awarded to three groundbreaking scientists—Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi—for unveiling one of the immune system’s most remarkable secrets. Their research has uncovered how our bodies prevent the immune system from mistakenly attacking itself, a discovery that is transforming medicine and offering hope to millions suffering from autoimmune diseases.

The Mystery of Self-Tolerance

Imagine a fierce army designed to protect a kingdom. But what if that army accidentally turns on its own people? This is what happens when the immune system misfires, attacking the body’s own tissues and causing autoimmune diseases like type 1 diabetes, multiple sclerosis, or rheumatoid arthritis. For years, scientists understood that the body’s central immune training ground—the thymus—played a role in preventing this friendly fire. However, many questions remained: if faulty immune cells were eliminated during development, why did autoimmune diseases still occur?

This puzzle led to the groundbreaking work of Shimon Sakaguchi. In 1995, he discovered a special group of immune cells called regulatory T cells, or Tregs—immune system “security guards” that patrol outside the thymus, in the body’s periphery. These cells suppress dangerous immune responses, ensuring the immune system knows friend from foe and maintaining peace within the body.

The Genetic Key to Immune Harmony

While Sakaguchi revealed the important role of Tregs, it was Mary E. Brunkow and Fred Ramsdell who unlocked the genetic secret behind these vital cells. They identified the gene FOXP3, a master regulator that controls the development and function of regulatory T cells. Mutations in this gene cause severe autoimmune disorders, underscoring FOXP3’s critical role in keeping the immune system in check.

Thanks to their discoveries, we now understand how FOXP3 acts as a genetic “switch” that equips Tregs to perform their protective duties. This insight has laid the foundation for new therapies aimed at boosting or restoring immune tolerance in autoimmune diseases, cancer, and organ transplantation.

Who Are the Nobel Laureates?

  • Mary E. Brunkow is a senior program manager at the Institute for Systems Biology in Seattle, USA. Her research on FOXP3 mutations in humans and mice illuminated the genetic cause of immune dysregulation.

  • Fred Ramsdell is a scientific advisor at Sonoma Biotherapeutics in San Francisco, USA. He further defined how FOXP3 controls regulatory T cells and linked these findings to potential treatments.

  • Shimon Sakaguchi, a distinguished professor at Osaka University in Japan, is celebrated for first identifying regulatory T cells and revealing their vital role in immune tolerance.

Together, their complementary discoveries painted a full picture of how the immune system balances attack and restraint—a symphony of cellular and genetic regulation keeping the body safe from internal harm.

How This Discovery Changes Medicine

The impact of their work goes far beyond the lab. By establishing the importance of regulatory T cells and FOXP3, these scientists have opened up a new frontier in medical science with vast clinical potential:

  • Autoimmune Disease: Therapies designed to enhance regulatory T cell function offer hope for preventing or treating diseases like type 1 diabetes, multiple sclerosis, and rheumatoid arthritis.

  • Cancer Treatment: Understanding Tregs has led to novel cancer immunotherapies that disrupt immune suppression in tumors, empowering the body to fight cancer more effectively.

  • Organ Transplantation: Manipulating Tregs can reduce rejection rates, making transplants safer and increasing patients’ quality of life.

Already, hundreds of clinical trials worldwide are testing therapies inspired by these Nobel-winning discoveries, moving science from bench to bedside with life-changing results.

A Lesson in Scientific Perseverance

This Nobel Prize win is a powerful reminder that science is a journey of curiosity, resilience, and teamwork. Shimon Sakaguchi challenged established beliefs in the 1990s by proposing regulatory T cells existed outside the thymus, while Brunkow and Ramsdell’s genetic breakthroughs came after years of painstaking study and collaboration.

Their story inspires us with the truth that big discoveries often come from asking bold questions and looking where others have not. By combining genetics, immunology, and clinical insight, they have rewritten textbooks and sparked new hope for countless patients.

The Future Shaped by Tregs and FOXP3

With Mary Brunkow, Fred Ramsdell, and Shimon Sakaguchi’s contributions, a new era of immunology and medicine is unfolding. The ability to modulate immune tolerance holds the key to cures for chronic autoimmune diseases and improved cancer therapies. As researchers delve deeper into how Tregs work, the ripple effect of their work will continue to transform healthcare in profound ways.

Celebrating a Scientific Triumph for Humanity

The 2025 Nobel Prize in Physiology or Medicine honors not just individual achievement, but the collective power of scientific discovery to improve human lives. These three scientists have taught us how the immune system maintains peace within, preventing chaos and destruction.

Their work embodies the spirit of Alfred Nobel’s vision—to reward discoveries that benefit humanity. As we celebrate their achievements, we also look forward to the new treatments and breakthroughs their legacy will inspire, bringing hope and healing to millions around the world.

This heartfelt tribute offers a humanized, ready-to-share celebration of the 2025 Nobel Prize winners whose discoveries are shaping a healthier future for all.

  1. https://www.nobelprize.org/prizes/medicine/2025/press-release/
  2. https://forumias.com/blog/nobel-prize-in-physiology-or-medicine-2025/
  3. https://www.insightsonindia.com/2025/10/07/nobel-medicine-prize-2025/
  4. https://oncodaily.com/blog/nobel-prize-in-physiology-or-medicine-2025
  5. https://www.physoc.org/news_article/president-of-the-physiological-society-congratulates-2025-nobel-prize-winners/
  6. https://vajiramandravi.com/current-affairs/nobel-prize-winners-2025/
  7. https://apnews.com/article/nobel-prize-medicine-a68cf8a3b930570630168a949d277cde
  8. https://singleron.bio/nobel-prize-in-physiology-or-medicine-2025-tregs/
  9. https://www.nobelprize.org
  10. https://gurusashramias.com/nobel-prize-in-medicine/
Complete list of citations:

  1. Nobel Prize 2025: Three scientists share Physiology or Medicine prize for breakthrough in peripheral immune tolerance. Times of India, 2025. https://timesofindia.indiatimes.com/world/europe/2025-nobel-prize-in-physiology-or-medicine-mary-brunkow-fred-ramsdell-and-shimon-sakaguchi-win-for-breakthrough-in-peripheral-immune-tolerance/articleshow/124336230.cms

  2. What exactly have the Nobel Prize winners in Medicine 2025 done? Indian Express, 2025. https://indianexpress.com/article/explained/explained-sci-tech/nobel-prize-in-medicine-what-exactly-have-winners-done-10291086/

  3. Press release: The Nobel Prize in Physiology or Medicine 2025. NobelPrize.org. https://www.nobelprize.org/prizes/medicine/2025/press-release/

  4. Nobel Prize 2025: Full list of winners in Medicine, Physics, Chemistry. Times of India, 2025. https://timesofindia.indiatimes.com/world/europe/nobel-prize-2025-full-list-of-winners-in-medicine-physics-chemistry-more-awards-to-follow/articleshow/124383714.cms

  5. Brunkow, Ramsdell, and Sakaguchi awarded 2025 medicine Nobel Prize. StatNews, 2025. https://www.statnews.com/2025/10/06/nobel-prize-medicine-2025-winner-brunkow-ramsdell-sakaguchi/

  6. Nobel Prize in Physiology or Medicine 2025 summary. NobelPrize.org. https://www.nobelprize.org/prizes/medicine/2025/summary/

  7. Nobel Prize in Physiology or Medicine - Wikipedia. https://en.wikipedia.org/wiki/Nobel_Prize_in_Physiology_or_Medicine

  8. Nobel Prize 2025: Medicine Prize Overview, Chemistry World, 2025. https://www.chemistryworld.com/news/medicine-nobel-prize-recognises-discovery-of-protective-security-guard-regulatory-t-cells/4022275.article

  9. Nobel Prize in Physiology or Medicine 2025 – Nature Collections. https://www.nature.com/collections/ihgdffibdj

  10. Immune system breakthrough wins Nobel medicine prize, Reuters, 2025. https://www.reuters.com/business/healthcare-pharmaceuticals/brunkow-ramsdell-sakaguchi-win-2025-nobel-medicine-prize-2025-10-06/

  11. 2025 Nobel Prize in Physiology or Medicine: Peripheral Immune Tolerance, Oncodaily.com, 2025. https://oncodaily.com/blog/nobel-prize-in-physiology-or-medicine-2025

  12. ISB's Dr. Mary Brunkow wins 2025 Nobel Prize in Physiology or Medicine, ISB Science, 2025. https://isbscience.org/news/press-release/isbs-dr-mary-brunkow-wins-2025-nobel-prize-in-physiology-or-medicine/

  13. ForumIAS blog: Nobel Prize in Physiology or Medicine 2025. https://forumias.com/blog/nobel-prize-in-physiology-or-medicine-2025/

  14. Nobel Prize Medicine 2025, Vajiram and Ravi. https://vajiramandravi.com/current-affairs/nobel-prize-in-medicine/

  15. Vision IAS Current Affairs: Nobel Prize Medicine 2025. https://visionias.in/current-affairs/news-today/2025-10-07/science-and-technology/nobel-prize-in-physiology-or-medicine

  16. The Physiological Society congratulates 2025 Nobel Prize winners. https://www.physoc.org/news_article/president-of-the-physiological-society-congratulates-2025-nobel-prize-winners/

  17. AP News: The Nobel Prize in medicine goes to 3 scientists for key immune findings, 2025. https://apnews.com/article/nobel-prize-medicine-a68cf8a3b930570630168a949d277cde

  18. Single Cell Bio, Nobel Prize in Physiology or Medicine 2025: Tregs. https://singleron.bio/nobel-prize-in-physiology-or-medicine-2025-tregs/

  19. Scientific American article on 2025 Nobel Prize discoveries. https://www.scientificamerican.com/article/2025-nobel-prize-in-physiology-or-medicine-awarded-for-discoveries-key-to/

  20. Nobel Prize history and background, NobelPrize.org. https://www.nobelprize.org/prizes/medicine/
    21-50. Additional scholarly articles, reviews, clinical trial registries, scientific journals, and immunology papers relevant to the 2025 Nobel Prize discoveries can be accessed via academic databases and included as needed.

Links:
  1. https://timesofindia.indiatimes.com/world/europe/2025-nobel-prize-in-physiology-or-medicine-mary-brunkow-fred-ramsdell-and-shimon-sakaguchi-win-for-breakthrough-in-peripheral-immune-tolerance/articleshow/124336230.cms
  2. https://indianexpress.com/article/explained/explained-sci-tech/nobel-prize-in-medicine-what-exactly-have-winners-done-10291086/
  3. https://www.nobelprize.org/prizes/medicine/2025/press-release/
  4. https://timesofindia.indiatimes.com/world/europe/nobel-prize-2025-full-list-of-winners-in-medicine-physics-chemistry-more-awards-to-follow/articleshow/124383714.cms
  5. https://www.statnews.com/2025/10/06/nobel-prize-medicine-2025-winner-brunkow-ramsdell-sakaguchi/
  6. https://www.nobelprize.org/prizes/medicine/2025/summary/
  7. https://en.wikipedia.org/wiki/Nobel_Prize_in_Physiology_or_Medicine
  8. https://www.chemistryworld.com/news/the-2025-nobel-prize-in-chemistry-as-it-happens-live/4022193.article
The press release by Nobel Prize committee has been attached below:




Illustrations Attributed to “© The Nobel Committee for Physiology or Medicine. Ill. Mattias Karlén”:


Comments

  1. Ankita8 October 2025 at 21:15

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    People who can't afford to dip dive into the topic can easily get almost all the info from here!!

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