Immunologist Frederick J. “Fred” Ramsdell, who received his undergraduate degree from UC San Diego and a doctorate in microbiology and immunology from UCLA, has been awarded the 2025 Nobel Prize in physiology or medicine. Ramsdell is recognized for his work on the human immune system.
Ramsdell shares the prize with Mary Brunkow of the Institute for Systems Biology in Seattle and Shimon Sakaguchi of Osaka University in Japan. The trio’s research focused on regulatory T cells, which play a key role in preventing the immune system from attacking the body’s own tissues.
According to the Nobel committee, their discoveries established peripheral immune tolerance as a field of study and have influenced efforts to develop therapies for cancer, autoimmune diseases, and organ transplantation. Their research has led to more than 200 ongoing clinical trials.
“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 first identified regulatory T cells (“T-regs”) in 1995 as immune cells that control other immune responses and help prevent autoimmune diseases. In 2001, Ramsdell and Brunkow discovered that mutations in a gene called Foxp3 made certain mice susceptible to fatal autoimmune disease; similar mutations were found responsible for IPEX syndrome in humans. By 2003, it was shown that Foxp3 governs 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., Ramsdell completed a fellowship at the National Institutes of Health before working at Immunex on T cell activation and tolerance. He also worked at Darwin Molecular, ZymoGenetics, Novo Nordisk, and served as chief scientific officer at the Parker Institute for Cancer Immunotherapy. He currently advises Sonoma Biotherapeutics.
Ramsdell joins eight other UCLA alumni who have won Nobel Prizes across fields including physiology or medicine, chemistry, economics, and peace. Eight UCLA faculty members have also been named Nobel laureates over past decades.
