Our immune system protects us from bacteria, viruses, and other foreign invaders. But to work properly, it must recognize the difference between “self” (our own cells) and “non-self” (foreign material). When this system fails, autoimmune diseases occur — for example, type 1 diabetes, rheumatoid arthritis, or lupus.
1. Shimon Sakaguchi found that some T cells act as “brakes” on the immune system. He called them regulatory T cells (Tregs). They prevent other immune cells from attacking the body’s own tissues.
2. Mary Brunkow and Fred Ramsdell later identified the gene that makes these cells work: FOXP3.
When this gene doesn’t function properly, the body can’t control its immune response, leading to severe autoimmune disease. Together, their discoveries showed that immune tolerance isn’t just established during immune cell development (in the thymus), but must be continuously maintained in the body through Tregs.
This work transformed immunology by explaining one of its biggest mysteries: how the immune system avoids self-destruction. It also laid the foundation for:
1. Autoimmune disease treatments that boost Treg function.
2. Transplant medicine, where increasing tolerance could prevent organ rejection.
3. Cancer therapy, where temporarily reducing Treg activity might help the immune system attack tumors more effectively.
The Nobel Committee honored Brunkow, Ramsdell, and Sakaguchi for uncovering how the immune system maintains peace within the body — balancing attack and tolerance — a discovery that has already inspired new therapies for many diseases.
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