A type of disease-fighting cells in the body — T cells — have a reputation for being ever-ready to fight invading infections. But that’s not the way they really work, found Vassiliki Boussiotis, an assistant professor at Harvard Medical School and a researcher at Dana-Farber Cancer Institute in Boston. Boussiotis and her colleagues found that the T cells’ normal state is to be quiet. Only when they receive a signal from a gene called “Tob” do T cells leap into action. Tob only sends out the signal when the body is threatened by infection and disease. The research finding has direct implications for the development of cancer vaccines and for safer organ transplants. The discovery was reported in the December 2001 issue of Nature Immunology. The research was supported by the National Institutes of Health.