Fig 1.

T cell recognition of cancer. In this scanning electron micrograph, a tumor-specific CD8+ killer T cell is shown in the act of recognizing a tumor cell expressing the cognate tumor antigen (arrow). Multiple other T cells not specific for any tumor antigens ignore the tumor cell. Tumor antigen recognition first involves generation of a tight junction with the tumor cell after which perforin is released to create pores in the tumor target. Granzymes released by the killer T cell can enter the cytoplasm of the tumor via these pores and activate effector caspases to induce apoptosis. (Magnification: ×5,000.)