Less death in the dying.

Diseases associated with aging are now the primary causes of death in developed countries. This is in part due to the long recognized exponential association of cancer with age and perhaps to a deterioration of the immune system with advanced age. Both prevention of tumorigenesis and immune function are critically dependent on apoptosis. In this study we examined apoptosis in mice of various age following gamma irradiation. We found a striking age-dependent decrease in radiation-induced apoptosis in splenic lymphocytes but not in colorectal epithelial cells. These observations may therefore provide a clue to the decline of immune function with age.