Apoptosis and the assessment of radiation injury.

Apoptosis is a necessary form of cell death for all multicellular organisms and is controlled by the action of genes that initiate, facilitate or inhibit the process. In addition to physiological triggers, apoptosis can follow cellular injury, such as exposure to ionizing radiation. Cell death following radiation serves as a means by which the possibility of cells surviving with potentially harmful genomic damage can be reduced. Apoptosis can be identified in tissues shortly after whole body radiation; but apoptotic cells are rapidly cleared by phagocytosis, and apoptosis is unlikely to serve as a useful long-term marker of previous radiation exposure.