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 work on the human immune system. Ramsdell shares the honor with Mary Brunkow from the Institute for Systems Biology in Seattle and Shimon Sakaguchi of Osaka University in Japan. Their collective research focused on regulatory T cells and how these cells prevent the immune system from attacking the body’s own tissues.
The Nobel committee highlighted that their discoveries established a new field called peripheral immune tolerance. This research has influenced therapeutic development for conditions such as cancer, autoimmune diseases, and organ transplantation. Currently, there are over 200 clinical trials underway based on their findings.
“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 excessive responses that could cause autoimmune diseases. In 2001, Ramsdell and Brunkow discovered that mutations in a gene named Foxp3 made mice prone to fatal autoimmune diseases; similar mutations were later found responsible for IPEX syndrome in humans. By 2003, it was shown by Sakaguchi, Ramsdell, and colleagues that Foxp3 is key to 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 earned his bachelor’s degree at UC San Diego before completing a doctorate at UCLA’s medical school program in microbiology and immunology—later merged with molecular genetics at UCLA College Division of Life Sciences—in 1987. He continued his career with fellowships at NIH and roles at Immunex, Darwin Molecular, ZymoGenetics, Novo Nordisk, Parker Institute for Cancer Immunotherapy (as chief scientific officer), and currently serves as scientific advisor at Sonoma Biotherapeutics.
Reflecting on his career after receiving another prestigious award—the Crafoord Prize—from Sweden’s Royal Academy of Sciences in 2017, Ramsdell stated: “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 alumni who have received Nobel Prizes across various disciplines including physiology or medicine (Ardem Patapoutian), chemistry (Randy Schekman), economic sciences (Elinor Ostrom), among others. Eight faculty members from UCLA have also been honored as Nobel laureates over past decades.
