Contribution of antioxidant enzymes to the adaptive response to ionizing radiation of human lymphoblasts

Purpose: To investigate whether the adaptive response to ionizing radiation triggered by a low-dose pre-exposure could be due to the activation of the antioxidant defence system. Materials and methods: Human lymphoblastoid AHH-1 cells were irradiated with a 0.02Gy gamma -radiation and 6h later were exposed to a 3Gy challenge dose according to a protocol allowing mutagenic adaptation. Controls included cells left unirradiated or exposed to a single dose (0.02Gy or 3Gy). The activities of the main cellular antioxidant enzymes (AOE)-copper-zinc superoxide dismutase (SOD1), manganese superoxide dismutase (SOD2), catalase (CAT), glutathione peroxidase (GPX), glutathione-S-transferase (GST), glutathione reductase (GSR) and glucose 6-phosphate dehydrogenase (G6PD)-were evaluated at different times after treatment. The levels of SOD2 and CAT proteins were also analysed using the immuno Western blot method. Results: Compared with non-irradiated controls, the effect of 3Gy alone was shown to increase GPX and CAT ac...