Nobel Prize in Medicine or Physiology: Peacekeepers and Inequities
S Krishnaswamy
ON October 6, the announcement of the 2025 Nobel Prize in Physiology or Medicine brought three scientists who had discovered the mechanism of immune system restraint to the attention of the world. Shimon Sakaguchi of Japan, along with Mary Brunkow and Fred Ramsdell of the United States, shared the award. Their findings identified a group of guardian cells that maintain peace within the body, preventing our immune system from attacking our own cells. Their work was referred to by the Nobel Committee as "discoveries concerning peripheral immune tolerance." It was a quest to understand how our body defends itself against itself.
The question at the core of this year's recognition is surprisingly straightforward: why doesn't our powerful immune system, which eliminates invaders, also eliminate us? The immune system is a living surveillance network that can detect invaders that are invisible to the naked eye. It distinguishes between friends and foes. But sometimes it fails. It may then turn against the body it defends. Conditions like multiple sclerosis, type 1 diabetes, and arthritis serve as reminders of what occurs when the body's defences mistake a neighbour for an enemy.
HOW ARE WE PROTECTED?
The immune system is a vast network that identifies what is part of the body from what is not, protecting the body from infection, injury, and disease. It functions through two main branches: the adaptive immune system, which gains experience to mount responses specific to pathogens, and the innate immune system, which provides quick but broad protection. One main component of this system is what we know as white blood cells. All jawed vertebrates have an adaptive system. This evolved about 45 crore years ago. It allows immune memory to persist long after the initial infection has ended. T-cells, a subset of white blood cells that serve as both a sentinel and a strategist, are at the core of this defence. These cells use precisely calibrated molecular cues to patrol tissues, identify aberrant or infected cells, and coordinate elimination. While some T cells coordinate larger immune responses or control inflammation, shielding healthy tissues from harm, others directly kill infected targets. T cells work in tandem with antibodies and other immune components to create a dynamic and adaptive defence that remembers previous threats and learns from each encounter, resulting in quicker and more effective defence the next time the same invader is encountered.
This year's Nobel story started in Japan in the 1980s when Shimon Sakaguchi, an immunologist, made a puzzling discovery. Newborn mice's immune systems collapsed when the thymus, the organ where T cells, a type of cell in our immune system, develop, was removed. The illnesses that the animals developed were similar to autoimmune diseases in humans. Sakaguchi reasoned that a unique type of cell that is part of the immune system restrains these destructive impulses. In 1995, he identified them as regulatory T cells, or Tregs. They controlled the immune system, designed to defend our cells rather than hunt down infections.
Mary Brunkow and Fred Ramsdell were investigating a genetic mystery in a strain of mice, known as Scurfy mice, at Celltech Chiroscience in Seattle, USA, at about the same time. The type of mice known as Scurfy mice was due to a mutant that emerged at Oak Ridge National Laboratory in the 1940s during radiation work as part of the Manhattan Project that created the atomic bomb. The mice's severe autoimmune disease was associated with the X chromosome. Brunkow and Ramsdell laboriously identified in 2001 a hitherto unidentified gene and the mutation in the X chromosome as the cause of the defect. They named the gene FOXP3. They later discovered that boys with a rare and fatal autoimmune disease had mutations in the corresponding human gene. In 2003, Sakaguchi demonstrated that FOXP3 is the master regulator for Treg development and function. His group and Ramsdell's group showed that expressing FOXP3 converted conventional T cells into Tregs while FOXP3 deficiency eliminated them.
BENEFITS OF CURIOSITY
These findings changed the view of immunity in medicine. For more than a century, researchers thought that the thymus eliminated T-cells that recognise cells belonging to the self in a single central examination, a process known as "central tolerance." Sakaguchi, Brunkow, and Ramsdell demonstrated that regulatory T-cells, which patrol the body's periphery and maintain the immune force's discipline, provide an additional layer of protection. Our bodies cannot exist without them. There are now around 200 clinical trials underway with Treg cells to try to control cancer, autoimmune diseases, and also to aid in organ transplantation treatments.
This Nobel Prize is a tale of tenacity that extends beyond the lab. Sakaguchi worked for years after the previous idea of suppressor T cells had lost credibility in the scientific community. Deciphering a gene that would alter medical textbooks took years for Brunkow and Ramsdell as well. Despite being geographically separated, their cooperation highlights the advantages of curiosity-driven science. The findings also reaffirm Alfred Nobel's original belief that research that benefits humanity should be honoured for both its basic understanding and practicality.
WHO COUNTS AS HUMANKIND?
For more than 500 years, Colonialism was an active force. For instance, eight countries comprising of the United Kingdom, France, Spain, Portugal, the Netherlands, Germany, Belgium, and Italy were the primary nations responsible for colonising the vast majority of the world. At the peak of the colonial era in 1914, European powers (Africa got sliced up in 1884 in the Berlin Conference) dominated about 84 per cent of the Earth's land area! Imperialism, as the highest form of capitalism, continues to dominate much of the world. The way science is perceived, cited and awarded is dominated by the USA that leads the countries of the Global North. These have had and continue to have a profound impact on the scientific enterprise, and shifting the axis of scientific influence will not happen overnight. It will require scientists in the Global North to commit to consciously decolonising their work and for those in the Global South to claim their rightful places in research.
The Nobel Prizes, however, continue to show a troubling trend. The fingerprints of colonialism and imperialism continue in the scientific enterprise. There have been 232 recipients of the Nobel Prize in Physiology or Medicine since the inaugural award in 1901. Just fourteen of them—only 6 per cent of them—have been female. White men from the United States and Europe make up the vast majority. There have not been any Black people. According to data from 2025, 111 laureates have been based in the United States, 104 in Europe, six in Japan, four in Canada and Australia, one in China, and none from Africa or India. Ten years ago, only one Asian woman—Tu Youyou of China—was recognised for discovering artemisinin, a medication derived from traditional Chinese medicine that has prevented millions of deaths from malaria. The award recognised her work in extracting the active compound from the Artemisia annua plant, a discovery that came after she researched ancient Chinese texts. She is the first scientist from China to win a Nobel Prize in a scientific category.
The three scientists from the global North this year—two from the United States and one from Japan—continue that trend. Even though their contributions are undeniably enormous, the disparity begs the question of whose science is valued, supported, and acknowledged. The focus of the awards has changed over time, from clinicians in the early 20th century to molecular biologists and geneticists after the mid-century. However, there is a lack of representation worldwide. Talent is evidently present everywhere, but opportunities and recognition are still not equally distributed. If Nobel Prizes are for honouring the "greatest benefit to humankind," it is worth asking, once again: who counts as humankind?
