Intracellular distribution of X-ray and heavy-ion induced 8-OHdG using immunostaining technique. LET dependence and detectability

Abstract

Intracellular distribution of 8-hydroxy-2'-deoxyguanosine (8-OHdG) has been examined by the immunostaining technique of human lung carcinoma A549 cells exposed to X-rays, carbon and iron ions. The LETs of carbon and iron ions were approximately 13 and 440 keV/μm, respectively. After fixation of irradiated cells, intracellular 8-OHdG was reactivated with diluted hydrochloric acid and detected by the immunostaining technique with the use of anti- 8-hydroxy-guanine antibody-FITC conjugates (Kamiya Biomedical. Co., USA). We also used the Fenton-reaction system to generate OH radicals as a positive control. The intracellular 8-OHdG exposed to carbon ions at a dose of 5 Gy was significantly detected and was distributed uniformly over the whole area of a nucleus. Furthermore, X-ray-induced 8-OHdG showed the same distribution as the case of carbon ions. In contrast, the intranuclear distribution of 8-OHdG by iron ions with a dose of 5 Gy seemed to be somewhat heterogeneous and the fluorescence intensity was less than those of X-rays and carbon ions. The distributions in other LETs in carbon and iron ions are under examination.