Implications of early apoptosis of infected cells as an important host defense

Apoptosis is widely recognized as being a host defense against viral infect ions, since viruses require live cells. There has been increasing acceptanc e of the view that apoptosis is also a defense against other intracellular pathogens and even against pathogens that adhere to host cells. An implicat ion of apoptosis being a host defense is a need to reassess to what extent the cell death at infection sites may constitute a protective host response . A concept stressed here is that infected cells are a hazard to other cell s and to the individual, so the benefits of early apoptosis are emphasized. Therefore, promoting the survival of infected cells, even though still fun ctional, may carry risks. A further consideration is the possibility that t he apoptotic stimulus of nutrient restriction may be acting in infection-in duced anorexia to promote apoptosis of infected cells, thereby serving as a non-specific host defense. (C) 2000 Harcourt Publishers Ltd.