Imaging a dying tumor

When T cells come across a tumor, they kill off the outer layers and then move in, say Boissonnas et al. on page 345. The authors use intravital microscopy to show that this infiltration and obliteration of the tumor is antigen dependent.

Intravital microscopy has previously revealed the killing strategy of T cells in lymphoid tissue. The T cells use a search-and-destroy tactic, moving rapidly through the tissue while constantly scanning for targets. When an enemy is identified, they stop, kill the intruder, and then resume the hunt. The T cells' method of killing inside a solid nonlymphoid tumor environment, however, is less certain. “We knew that the immune system can reject tumors,” says senior author Sebastian Amigorena, “but we didn't really understand how T cells function inside the tumor.”

Amigorena and...