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 contributions to understanding the human immune system. Ramsdell is currently a scientific advisor at Sonoma Biotherapeutics in San Francisco.
Ramsdell shares the Nobel Prize with Mary Brunkow from the Institute for Systems Biology in Seattle and Shimon Sakaguchi of Osaka University in Japan. Their research focuses on regulatory T cells, which are essential for preventing the immune system from attacking healthy tissue.
According to the Nobel committee, their work established a new area of research called peripheral immune tolerance and has led to development efforts around regulatory T cell–based therapies for conditions such as cancer, autoimmune diseases, and organ transplantation. More than 200 clinical trials are underway that build upon these discoveries.
“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 and showed they help control other immune cells’ activity to prevent harmful overreactions that can cause autoimmune diseases. In 2001, Ramsdell and Brunkow discovered that mutations in a gene named Foxp3 made mice susceptible to fatal autoimmune disorders; similar mutations were later linked to IPEX syndrome in humans. By 2003, Sakaguchi, Ramsdell, and colleagues demonstrated that Foxp3 governs how regulatory T cells develop.
Olle Kämpe, chair of the Nobel Committee, said: “Their discoveries have been decisive for our understanding of how the immune system functions and why we do not all develop serious autoimmune diseases.”
After earning his undergraduate degree from UC San Diego in biochemistry and cell biology, Ramsdell completed his Ph.D. at UCLA’s medical school before continuing postdoctoral work at the National Institutes of Health. He then worked at several biotechnology companies including Immunex, Darwin Molecular, ZymoGenetics, Novo Nordisk, and served as chief scientific officer at Parker Institute for Cancer Immunotherapy before joining Sonoma Biotherapeutics’ advisory board.
Ramsdell reflected on his career after receiving another major award: “I fell in love with immunology in college,” he said following receipt of the Crafoord Prize from Sweden’s Royal Academy of Sciences in 2017. “It touches so many aspects of our biology that I felt like it was an important thing to work on.”
With this latest honor, Ramsdell joins eight other UCLA graduates who have received Nobel Prizes across fields such as medicine, chemistry, economics, and peace. Eight faculty members affiliated with UCLA have also been named Nobel laureates.
