What is immunotherapy?
Ask the doctor
About 20 years ago, two scientists — one in the United States and one in Japan — were studying T cells, immune system cells that attack foreign things. They weren't studying cancer. They were just trying to figure out how T cells work. Each of the scientists found a chemical on the surface of T cells that had not previously been discovered. One chemical was called PD-1, and the other CTLA-4. What did they do? When stimulated, the chemicals kept the T cells from attacking things: they applied the brakes.
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