Immunologist Frederick J. “Fred” Ramsdell has been awarded the 2025 Nobel Prize in physiology or medicine for his research on the human immune system. Ramsdell, who received his undergraduate degree from UC San Diego and a doctorate in microbiology and immunology from UCLA, shares the prize with Mary Brunkow of the Institute for Systems Biology in Seattle and Shimon Sakaguchi of Osaka University in Japan.
Their work focused on regulatory T cells, also known as T-regs, which play a critical role in preventing the immune system from attacking the body’s own tissues. The Nobel committee highlighted that these discoveries have established a new field called peripheral immune tolerance and have led to ongoing clinical trials exploring therapies for cancer, autoimmune diseases, and organ transplantation.
“Fred Ramsdell’s research on the immune system has transformed our understanding of autoimmune diseases and led to treatments that are saving lives around the world,” said UCLA Chancellor Julio Frenk. “From improving care for conditions like multiple sclerosis to advancing cancer therapies, his work is driving medical breakthroughs that will shape the future of human health. I hope Bruins everywhere take pride in this well-deserved global recognition.
“At a time of unprecedented challenges to research funding, once again the United States leads the way in medical breakthroughs recognized by the Nobel Prize,” Frenk added.
Sakaguchi was first to identify regulatory T cells in 1995, showing their role as regulators within the immune system to prevent overactive responses that can result in autoimmune disease. In 2001, Ramsdell and Brunkow discovered that mutations to a gene named Foxp3 caused severe autoimmune disorders in mice; soon after they found similar mutations were responsible for IPEX syndrome in humans. By 2003, it was confirmed that Foxp3 controls development of regulatory T cells.
“Their discoveries have been decisive for our understanding of how the immune system functions and why we do not all develop serious autoimmune diseases,” said Olle Kämpe, chair of the Nobel Committee.
After earning his Ph.D. at UCLA, Ramsdell worked at several institutions including Immunex and Darwin Molecular before taking leadership roles at ZymoGenetics, Novo Nordisk, and later serving as chief scientific officer at Parker Institute for Cancer Immunotherapy. He is currently an advisor at Sonoma Biotherapeutics.
Ramsdell joins eight other UCLA alumni who have previously received Nobel Prizes across fields such as medicine, chemistry, economics, and peace. Eight UCLA faculty members have also been honored with Nobel Prizes.
“I fell in love with immunology in college,” Ramsdell said after receiving another prestigious award in 2017. “It touches so many aspects of our biology that I felt like it was an important thing to work on.”
