Input Stories

Three scientists have been awarded the Nobel Prize in Physiology or Medicine for their discoveries about the human immune system (AP).

What’s going on: “The work by Mary E. Brunkow, Fred Ramsdell and Dr. Shimon Sakaguchi uncovered a key pathway the body uses to keep the immune system in check, called peripheral immune tolerance. Experts called the findings critical to understanding autoimmune diseases such as Type 1 diabetes, rheumatoid arthritis and lupus.”

• The three scientists, two of whom are from the U.S. and one of whom is from Japan, previously “identified the importance of what are now called regulatory T cells,” which are being used to improve organ transplant success and find better treatments for autoimmune disease, among other applications.
• The award, the first of the 2025 Nobel Prizes to be announced, was given Monday.

About the winners: Brunkow, 64, is a senior program manager at the Institute for Systems Biology in Seattle, Washington. Ramsdell, 64, is a scientific adviser for Sonoma Biotherapeutics in San Francisco, California. Sakaguchi, 74, is a distinguished professor at Osaka University’s Immunology Frontier Research in Japan.
 
Their discoveries: Scientists previously believed the human body regulated the immune system “only in a centralized fashion,” with immunity fighters such as T cells getting “trained” to spot and remove infected and abnormal cells, and those that malfunction and trigger autoimmunity being removed by the thymus gland.

• “The Nobel winners unraveled an additional way the body keeps the system in check if immune cells later get confused and mistake human cells for intruders, which is what happens when a person has an autoimmune disease.”
• In 1995, Sakaguchi “discovered a previously unknown T cell subtype … that also could tamp down overreactive immune cells like a biological security guard.”
• In 2001, Brunkow and Ramsdell “figured out that a particular mutation in a gene called Foxp3 was to blame” for an autoimmune disease in mice—and “quickly realized it could be a major player in human health, too.”
• Sakaguchi linked his discoveries with Brunkow and Ramsdell’s “to show the Foxp3 gene controls the development of those regulatory T cells so they’re able to curb other, overreactive cells.”

Why it’s important: The trio’s discoveries have “opened a new field of immunology,” according to Karolinska Institute rheumatology professor Marie Wahren-Herlenius.