Research in our laboratory focuses on biological processes in which cells die and tissue damage occurs. We began this study long ago in exploring the compositional and mechanistic nature of a cell-killing activity in leukocyte-produced crude protein preparations, which we then called ‘cytotoxin’. The cell-killing protein that we isolated is now called tumor necrosis factor (TNF). It has since then been found by us and others to have, besides cell-death induction, a wide range of other effects on cell function.