Nobel Prize winner Shimon Sakaguchi reflects on how he discovered regulatory T cells
SMRTR summary
Twenty-five years ago, immunologist Shimon Sakaguchi made a discovery that most of his peers thought was impossible: immune cells whose job wasn't to attack invaders, but to keep the peace.
Sakaguchi had just won the 2025 Nobel Prize in Physiology or Medicine for discovering regulatory T cells, or "Tregs" - cellular peacekeepers that prevent the immune system from turning against the body itself. Back in the 1980s, the scientific community had largely dismissed the existence of such cells.
The breakthrough came through an elegant experiment. When Sakaguchi removed the thymus from newborn mice, they developed autoimmune diseases. But when he injected normal T cells back into these mice, the diseases disappeared.
"I was convinced that autoimmune diseases can be produced in healthy animals by just manipulating the immune system," Sakaguchi says.
His colleague Zoltan Fehervari coined the term "peacekeepers" for these cells, and it stuck. The name proved prophetic - scientists later discovered Tregs don't just suppress immune responses, they also promote tissue repair.
Now, more than 200 clinical trials are underway exploring how to manipulate these cellular peacekeepers to treat cancer, autoimmune diseases, and chronic infections.
SMRTR provides this summary for quick context. The original article belongs to Scientific American.
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