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Against the Odds: Mary Brunkow and the Discovery That Transformed Immunology

  • Writer: U of T Scientista
    U of T Scientista
  • Nov 28
  • 3 min read

By Fangfei Cai

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Only 2% of Nobel Prizes in the sciences have gone to women since the awards began in 1901. That’s a statistic so small, it could slip past without notice; yet behind this number are generations of women who kept pushing, researching, publishing and proving their ideas against the odds. In 2025, that 2% gained a new name: Mary E. Brunkow, an American molecular biologist and immunologist who received the Nobel Prize in Physiology or Medicine for her work and reshaping how scientists think about the immune system. 


Mary Elizabeth Brunkow, born in 1961 in Portland, Oregon, developed an early fascination with how living systems regulate themselves. She earned a B.Sc in molecular and cellular biology from the University of Washington in 1983, and completed her PhD in molecular biology at Princeton University in 1991. From 1990 to 1994, she conducted postdoctoral research in Toronto’s Samuel Lunenfeld Research Institute - now part of Sinai Health - before moving into industry in Seattle where she began investigating immune disorders in mice. 


Brunkow’s Nobel-winning research took shape in the late 1990s at Immunex Corporation in Seattle, a small biotech startup tucked away in Bothell, just North of Seattle, that was trying to develop new drugs. Brunkow was a new hire, she was young, curious, and determined to prove herself. Brunkow and her colleague Dr. Fred Ramsdell was studying a strange and deadly disease in mice, where the immune system attacked the body and caused severe inflammation and organ failure. Eventually, Brunkow discovered that the problem came from a single damaged gene, which she named the FOXP3 gene. FOXP3 turned out to be extremely important. It creates special “peacekeeper” immune cells called regulatory T cells that stop the immune system from attacking the body. When FOXP3 is broken, these peacekeepers never form, and the immune system loses control.This discovery changed how scientists understood the immune system, giving an explanation to a rare human disease called IPEX syndrome, caused by FOXP3 mutations. Around the same time, Japanese scientist Dr. Shimon Sakaguchi found similar peacekeeper cells in the body, confirming Brunkow’s work from another angle. Together, their findings showed how the body prevents harmful autoimmune reactions and opened the door to new medical treatments, including cancer immunotherapy and organ transplantation. On October 6, 2025, Dr. Brunkow, Dr. Ramsdell, and Dr. Sakaguchi were awarded the Nobel Prize in Physiology or Medicine for their groundbreaking discovery.


Reflecting on her journey, Brunkow told KOMO News that the moment still felt unreal. “It’s gratifying to see how meaningful a Nobel Prize is,” she said. “I’m proud and humbled—still in complete disbelief. It was such a surprise, quite overwhelming.” From her early days as a new hire at a small biotech startup north of Seattle, her story captures the heart of discovery itself: driven by curiosity, persistence and purpose. Her Nobel Prize not only celebrates a breakthrough in understanding the immune system, but also expands the 2%, proving that female representation in discovery matters. Each new name added to that small statistic brings the scientific community one step closer to recognition and progress. 


References 

1. Nobel Prize. (2025, October 7). The Nobel Prize in Physiology or Medicine 2025 – Press Release. Retrieved from 

3. Reuters. (2025, October 7). Mary Brunkow, Fred Ramsdell, and Shimon Sakaguchi share 2025 Nobel Prize for discoveries in immune regulation. Retrieved from

4. Nature News. (2025, October 8). Nobel Prize 2025: How FOXP3 unlocked the secrets of immune tolerance.Retrieved from https://www.nature.com/articles/d41586-025-03193-3 5. ScienceAlert. (2025, October 8). Surprising immune cell discovery wins 2025 Nobel Prize — here’s the science behind FOXP3 and Tregs. Retrieved from https://www.sciencealert.com/surprising-immune-cell-discovery-wins-2025-nobel-prize-h eres-the-science 

6. KOMO News. (2025, October 7). Nobel Prize winner Mary Brunkow reflects on her discovery and surprise at the award.Retrieved from 

 
 
 

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