Immunologist Frederick J. “Fred” Ramsdell, an alumnus of both UC San Diego and UCLA, has been awarded the 2025 Nobel Prize in physiology or medicine for his research on the human immune system. Ramsdell shares the prize with Mary Brunkow from the Institute for Systems Biology in Seattle and Shimon Sakaguchi of Osaka University in Japan. Their work focused on regulatory T cells, which play a key role in preventing the immune system from attacking the body’s own tissues.
The Nobel committee stated that their discoveries have established a new field called peripheral immune tolerance and led to new approaches for treating cancer, autoimmune diseases, and organ transplantation. Over 200 clinical trials are currently underway based on this research.
“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.
Shimon Sakaguchi first identified regulatory T cells (T-regs) in 1995, showing that they help control other immune cells and prevent overactive responses that could cause autoimmune diseases. In 2001, Ramsdell and Brunkow discovered that mutations in a gene called Foxp3 made mice susceptible to fatal autoimmune diseases. They later found similar mutations caused IPEX syndrome—a severe autoimmune disease—in humans. By 2003, Sakaguchi, Ramsdell, and colleagues showed that Foxp3 was essential for developing 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.
Ramsdell completed his undergraduate studies at UC San Diego before earning his doctorate at UCLA’s medical school in microbiology and immunology. He went on to hold positions at several organizations including Immunex, Darwin Molecular, ZymoGenetics, Novo Nordisk, and served as chief scientific officer at the Parker Institute for Cancer Immunotherapy. He is currently a scientific advisor at Sonoma Biotherapeutics.
Reflecting on his career after receiving another major award in 2017, Ramsdell said: “I fell in love with immunology in college. It touches so many aspects of our biology that I felt like it was an important thing to work on.”
Ramsdell joins eight other UCLA graduates who have received Nobel Prizes across various fields such as physiology or medicine, chemistry, economics sciences, and peace. Eight faculty members from UCLA have also been named Nobel laureates over past decades.
