Scanning Electron Micrograph of a Cytotoxic Lymphocyte Destroying a Tumor Cell:
CTL Attaching to a Tumor Cell

The CTL is the cell on the right. The T-cell receptor/CD8 molecules on CTLs recognize corresponding peptides bound to MHC-I molecules on the tumor cell. After binding, the CTL secretes perforins and granzymes to put pores in the membrane of the tumor cell and trigger apoptosis.