Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi won the 2025 Nobel Prize in Physiology or Medicine.
They were recognized “for their discoveries concerning peripheral immune tolerance,” announced the Karolinska Institute in Stockholm.
The three scientists share 11 million Swedish kronor, about £871,400. “We could only reach Sakaguchi,” said Prof Thomas Perlmann.
Their research explains how the immune system avoids attacking the body’s own cells, preventing autoimmune diseases.
Sakaguchi discovered regulatory T-cells, or T-regs, which act as brakes on the immune system. “They keep us safe,” he said.
Brunkow and Ramsdell found that the FoxP3 gene controls these T-regs. Mutations in it cause rare autoimmune disorders.
“Without these cells, the immune system destroys itself,” said Prof Adrian Liston of the University of Cambridge.
Their discoveries reshaped medicine, inspiring new treatments for autoimmune diseases, organ transplants, and even cancer.
“For autoimmune disease, we boost T-regs,” said Prof Marie Wahren-Herlenius. “For cancer, we suppress them.”
Experts called the award long overdue. “This discovery changed everything,” said Prof Danny Altmann. “It redefined immune balance.”
