The existence of a unique kind of immune cell the killer lymphocyt- which destroys other cells in a highly specific manner, has fascinated immunologists for almost half a century. How do these cells, whose precursors have lived in communal harmony with their host, decide that some of their cohabitants must die? And how do they kill them? The definition of killer lymphocytes came from discovery of their roles in a wide range of in vivo phenomena such as transplant rejection, virus infection and its related immunopathologies, and anti-tumor responses. Yet for the most part almost everything we...

The existence of a unique kind of immune cell the killer lymphocyt- which destroys other cells in a highly specific manner, has fascinated immunologists for almost half a century. How do these cells, whose precursors have lived in communal harmony with their host, decide that some of their cohabitants must die? And how do they kill them? The definition of killer lymphocytes came from discovery of their roles in a wide range of in vivo phenomena such as transplant rejection, virus infection and its related immunopathologies, and anti-tumor responses. Yet for the most part almost everything we...