Radiation-induced apoptosis of human peripheral T cells: Analyses with cDNA expression arrays and mitochondrial membrane potential assay

We examined sequential changes in post-irradiated peripheral blood T cells taken from normal volunteers, by using targeted Atlas cDNA Expression Array s and mitochondrial membrane potential assay. At 1 and 3 hours after 5 Gy i rradiation, changes of gene expression were examined by targeted Atlas cDNA Expression Arrays using Apoptosis Array. The Atlas Human Apoptosis Array i ncludes 205 key genes that are known to control apoptosis, including extrac ellular and cytoplasmic effectors. Concerning Fas, no significant changes o f spot intensities were identified between irradiated T cells and non-irrad iated ones at both 1 h and 3 h after 5 Gy irradiation. Caspase families, in cluding caspases 9 and 3 also showed no changes between these two groups. A n apoptosis regulator bclw showed a remarkable decrease in irradiated T cel ls. These results suggested that irradiation induced direct apoptosis of T cells by changing the membrane potential of mitochondria. Using a CCD camer a-equipped fluorescence microscope and MitoCapture, a mitochondrial membran e potential indicator, we demonstrated 5 Gy radiation induced loss of membr ane potential, i.e., an early stage of apoptosis, in human peripheral blood T cells at 10 hours after irradiation.