Effect of aging on UVC-induced apoptosis of rat splenocytes

UVC-induced apoptotic symptoms such as morphological changes, DNA fragmenta tion, Bcl-2 and Bar protein expression were examined in primary splenocyte cultures from young (3 months) and old (24 months) rats. The activities of AP-I and CRE transcription factors in UVC-irradiated splenocytes were also assessed. At 24 h after UVC irradiation 40% of cells derived from young rat s were found to be apoptotic, which was twice as much as in splenocytes fro m old rats. Apoptosis in cells from old rats did not give typical symptoms like a "DNA ladder" and Bcl-2 protein downregulation, in contrast to spleno cytes from young rats. No AP-1 transcription factor activity was found in U VC-irradiated splenocytes from old animals and only a trace activity in spl enocytes from young animals. This indicates that, UVC-induced apoptosis in rat splenocytes is practically AP-1 independent and that cells from old rat s are less sensitive to UVC irradiation than splenocytes from young rats.