The interferons and cell death: guardians of the cell or accomplices of apoptosis

The interferons (IFNs) play an integral role in cellular host defense again st virus infection and conceivably tumorigenesis. Despite over 50 years of research, however; the molecular mechanisms underlining IFN action remain t o be fully elucidated, in part because of the large number of genes, with a n uncharacterized function that appears to be induced by these cytokines. A lthough the majority of in vitro studies indicate that IFNs antiviral prope rties involve inhibiting viral replication while maintaining the integrity of the cell, numerous reports have now implicated that a number of IFN-indu ced genes, IFN transcriptional regulatory factors and IFN signaling molecul es can also mediate apoptosis. Here, we review some of what is known about IFN's ability to invoke programmed cell death as part of an intricate arsen al intended to prevent viral infection and malignant disease.