Tumor cells produce antigens that should be recognized by the immune system, yet are not, allowing cancer cells to proliferate. A report by researchers at Johns Hopkins University helps explain why the strategy of stimulating T cells to attack cancer hasn't worked, and why newer approaches try to call all of the immune machinery into play against tumors.

Writing last week in the Proceedings of the National Academy of Sciences, the scientists showed that tumors in a mouse model grew unchecked despite treatment with T cells primed