CELL DEATH BY MURDER. “Cytotoxic lymphocytes (CTL) and Natural Killer (NK) cells owe their names to their ability to induce death of their target cells. In order to avoid propagation of a virus, cytotoxic cells attack and kill the infected cells and they use several effector mechanisms in order to do so.”
https://celldeath.files.wordpress.com/2010/11/lopezself_munoz.pdf