The Impossible Made Possible: 2025 Nobel Laureates in Medical Science
Anupam Guha
October 17, 2025
In 2025, the Nobel Prize in Medicine was awarded to a groundbreaking trio whose pioneering work pushed the boundaries of scientific possibility. The recipients of the Nobel Prize in Medicine are Mary E. Brunkow and Fred Ramsdell from the United States, and Shimon Sakaguchi from Japan. They are awarded for their discovery of peripheral immune tolerance. This is a process of the immune system that prevents the body's own components and harmless foreign substances from being attacked or destroyed. The laureates will receive a medal, a certificate, and 11 million Swedish kronor, which will be shared equally among them. Their remarkable achievements have opened new horizons in medical science, transforming what was once thought impossible into reality. Their innovative contributions promise to revolutionize healthcare and improve countless lives worldwide.
Three scientist received the Nobel Prize in Medicine for their significant contributions. On Monday, October 6, the Nobel was announced by the Karolinska Institute in Sweden. Among the awardees, Mary E. Brunkow was born in the United States in 1961. She earned her Ph.D. from Princeton University in the United States. Currently, she is working as a Senior Program Manager at the Institute for Systems Biology in Seattle, USA. Fred Ramsdell was born in the United States in 1960. He obtained his Ph.D. from the University of California in Los Angeles, USA. He is currently working as a Scientific Advisor at Sonoma Biotherapeutics in San Francisco, USA. Shimon Sakaguchi from Japan was born in 1951. In 1983, he earned his Ph.D. from Kyoto University in Japan. He is working as a Distinguished Professor at the Osaka Immunology Frontier Research Centre, Osaka University, Japan.
Immunity is the body's natural ability to fight against disease-causing organisms or pathogens, such as viruses and bacteria, thereby protecting the body. It operates through the body's own defence or immune system, helping prevent disease and reducing the risk of infection. The immune response has two types: self-tolerance and induced tolerance, both of which play an integral role in protecting the body from harmful inflammation. The immune system can distinguish self-antigens and does not react against them, a process known as self-tolerance. When this ability is lost, and the body begins attacking its own cells, it can lead to autoimmune diseases. Throughout a person's life, an active process of self-immunity development occurs. During development, auto reactive lymphocytes are eliminated, and regulatory T-cells help keep their activity in check during blood circulation.
Peripheral immunity refers to the immune processes that occur outside the central nervous system in the peripheral organs and tissues of the body. In this process, the body can mount appropriate immune responses, maintain immune tolerance, and protect against various infectious and inflammatory diseases. It serves as an interconnected system between the peripheral nervous system and the immune system, aiding in inflammation control and tissue healing.
Each of us possesses a robust immune system that not only fights external bacteria and viruses but also knows which of our body's cells should not be attacked. Every day, we come into contact with various pathogens that change over time and can take different forms, making them difficult to identify. This leads to the emergence of new diseases. The normal functioning of the body's immune defence becomes challenging; if it fails to distinguish healthy cells from harmful ones, autoimmune diseases can develop. Additionally, stem cells or bone marrow play a highly effective role in the treatment of incurable diseases. As a result, their application is increasing, though there are risks involved. Therefore, understanding how our immune system works—particularly how it receives signals about whom not to attack—is very important.
One of the key tools of our immune system is T-cells. Helper T-cells constantly patrol the body, alerting the immune system when they sense danger. Killer T-cells then attempt to neutralize viruses or other pathogens. Previously, it was believed that the thymus gland (located in the upper chest, between the sternum and lungs) regulated how the immune system functions. This gland remains especially active in children. T-cells, including helper and killer T-cells, are produced in the thymus and then enter the bloodstream, circulating throughout the body.
In 2025, these three scientists provided a detailed explanation of the immune system and physiological functions, and they specifically identified T-cells, which opened a new horizon in medical science.
In the mid-1990s, Shimon Sakaguchi challenged the prevailing belief by asserting that certain types of T-cells act as "security guards" within our immune or disease-resistance system. Essentially, these cells suppress overly aggressive immune responses. He conducted experimental work with albino rats lacking the thymus gland, known as those with autoimmune diseases. T-cells were introduced into their bodies from outside. In this context, he identified a class of T-cells that only send messages to calm down the cells that are abnormally activated, playing the role of regulatory T-cells. However, these findings did not initially create a significant impact in the scientific community.
Meanwhile, two American scientists, Mary E. Brunkow and Fred Ramsdell, conducted research on same albino rats with autoimmune conditions involving the FOXP3 gene mutation. Their research over several years established that this gene controls the development of regulatory T-cells, a discovery that aligns with what Sakaguchi had previously attempted to demonstrate. Their combined work was ultimately awarded the Nobel Prize now.
It is evident that the discovery of regulatory T-cells and the FOXP3 gene will play a significant role in human immune defense research. Tumors in cancer are often surrounded by regulatory T-cells, forming a "protective barrier." Researchers are investigating how to breach this barrier so that the immune system can better reach and rapidly control cancerous cells. Similarly, in the case of autoimmune diseases, increasing the number of regulatory T-cells may help prevent attacking healthy tissues. Scientists are optimistic that their work on these cells will lay the foundation for a new research field. This discovery has also opened various possibilities in medical science.Currently, clinical trials are underway based on this breakthrough, with hopes that, in the future, the discoveries will lead to effective treatments for autoimmune diseases and more efficient methods for cancer therapy.
The achievements of the 2025 Nobel Laureates exemplify the extraordinary potential of human ingenuity and perseverance. By turning the impossible into reality, they have not only advanced medical science but also paved the way for a healthier future. Their groundbreaking work inspires continued innovation and reminds us that with determination and vision, even the most formidable challenges can be overcome.
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