Often called peacekeepers, these cells help prevent our immune systems from going out of control.
For most of the 20th century, scientists pictured the immune system as the body’s ever-vigilant army—standing guard against germs, viruses, and rogue cells. Yet one question remained: What keeps this army from mistakenly attacking the body itself?
For millions with autoimmune and inflammatory diseases like Type 1 diabetes or lupus, the question is personal—these lifelong illnesses bring painful symptoms and harsh immune-suppressing treatments.
This year’s Nobel Prize in Physiology or Medicine honored the discoveries that transformed that understanding. Researchers Mary E. Brunkow, Fred Ramsdell, and Shimon Sakaguchi identified a rare class of immune cells—regulatory T cells, or Tregs. These cells help prevent our immune systems from going out of control through a specialized gene called FOXP3. Often called peacekeepers, these Tregs changed how scientists think about autoimmunity, inflammation, and balance in the immune system itself.
“It [the Nobel award announcement] gave me goosebumps,” immunologist Anuradha Ray, remembering a recent conference where she sat beside Sakaguchi, told The Epoch Times. “This discovery has shaped the way we think about immune balance—and what happens when that balance breaks down.”
The path to this breakthrough wound through decades of controversy—and nearly disappeared amid skepticism.
The Paper That Changed Everything
Thirty years ago, Sakaguchi published a paper that challenged long-standing beliefs about the immune system. For decades, many scientists had dismissed the idea that certain immune cells could actively stop the immune system from attacking the body. Some early studies in the 1970s hinted at this, but the results were inconsistent—and the idea of “suppressor” T cells fell out of favor.
“There was a lot of skepticism in the 1990s,” Dr. Ethan Shevach, an immunologist and scientist emeritus at the National Institutes of Health who helped validate Sakaguchi’s findings, told The Epoch Times. “The whole concept of suppressor T cells had been under a cloud.”
What made Sakaguchi’s findings different was that he pinpointed a way to identify these mysterious cells. He found they carried a specific marker on their surface called CD25—a kind of biological flag that made the cells easier to detect and study. Shevach, intrigued, repeated the experiments in his own lab at the NIH.
“The data was solid,” he said. “It helped convince a lot of people, including me, that this was real.”
Sakaguchi’s findings nudged the field forward. Many still questioned whether these were truly a unique class of cells—or just ordinary T cells behaving differently under certain conditions.
Researchers had to prove these cells weren’t just active—they were specialized. The search turned to what made them work.
