A life in context
The person behind the prize
Sakaguchi trained in medicine in Japan and devoted his research to a difficult question: how does the immune system avoid attacking the body’s own tissues? His work established that protection from autoimmunity requires active control as well as the removal of dangerous immune cells.
The contribution
In 1995, he identified regulatory T cells that restrain immune responses. Later research connected these cells to Foxp3, bringing together the cellular and genetic explanations of peripheral immune tolerance.
The idea in plain language
An immune system must fight threats without destroying the body. Removing some dangerous cells early in their development is not enough: immune responses also need active restraint in the rest of the body.
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