Bruin brilliance: UCLA alumnus Frederick Ramsdell wins the Nobel Prize

When Fred Ramsdell lost cellphone reception during a hiking trip deep in the Rocky Mountains, he had no idea history was calling. Twelve hours later, he emerged from the wilderness to discover he’d won the 2025 Nobel Prize in physiology or medicine.

The immunologist and UCLA alumnus, who shared the honor with researchers Mary Brunkow and Shimon Sakaguchi, helped answer one of biology’s most profound questions: Why doesn’t the immune system attack the body it’s meant to protect?

The trio’s collective research identified and pinpointed the origin of regulatory T cells — “T-regs” — a subclass of immune cells that act as peacekeepers, patrolling other immune cells and damping down overzealous responses that might threaten the body’s own tissues. Their findings have revolutionized treatment for autoimmune diseases like multiple sclerosis, Crohn’s disease and arthritis, while opening doors to cancer and stem-cell therapies. More than 200 clinical trials are now underway based on their work.

“Fred Ramsdell’s research has transformed our understanding of autoimmune disease and led to treatments that are saving lives around the world,” said UCLA Chancellor Julio Frenk. “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.”

Ramsdell’s Nobel journey began in earnest at UCLA, where he earned his doctorate in microbiology and immunology in 1987 under the mentorship of medical school professor Sidney Golub. He went on to a fellowship with the National Institutes of Health and a pioneering career in biotechnology. Today, he serves as a scientific advisor for Sonoma Biotherapeutics.

Ramsdell’s breakthrough came in 2001, after Sakaguchi had first identified T-regs. With Brunkow, Ramsdell discovered that a mutation in a gene the duo called Foxp3 could cause devastating autoimmune disease in mice; it did the same humans, they went on to find. Two years later, Ramsdell, Sakaguchi and a colleague demonstrated that Foxp3 governs the body’s production of regulatory T cells, providing a genetic blueprint for immune tolerance. Their work is recognized today as a foundational discovery in modern immunology.

“I certainly didn’t expect to win the Nobel Prize,” Ramsdell told the New York Times after returning from his hike. “I was just grateful and humbled by the recognition — and happy to share it with my colleagues.”

Ramsdell joins an illustrious Bruin legacy: Eight other UCLA alumni and eight faculty members have earned Nobel honors. As UCLA Chancellor Frenk noted when Ramsdell won the prize, “Once again, UCLA research proves that discovery here doesn’t just change the conversation — it changes lives.”

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