Mitochondrial DNA alterations of peripheral lymphocytes in acute lymphoblastic leukemia patients undergoing total body irradiation therapy

BACKGROUND Mitochondrial DNA (mtDNA) alterations, including mtDNA copy number and mtDNA 4977 bp common deletion (CD), are key indicators of irradiation-induced damage. The relationship between total body irradiation (TBI) treatment and mtDNA alterations in vivo, however, has not been postulated yet. The aim of this study is to analyze mtDNA alterations in irradiated human peripheral lymphocytes from acute lymphoblastic leukemia (ALL) patients as well as to take them as predictors for radiation toxicity. METHODS Peripheral blood lymphocytes were isolated from 26 ALL patients 24 hours after TBI preconditioning (4.5 and 9 Gy, respectively). Extracted DNA was analyzed by real-time PCR method. RESULTS Average 2.31 times mtDNA and 0.53 fold CD levels were observed after 4.5 Gy exposure compared to their basal levels. 9 Gy TBI produced a greater response of both mtDNA and CD levels than 4.5 Gy. Significant inverse correlation was found between mtDNA content and CD level at 4.5 and 9 Gy (P = 0.037 and 0.048). Moreover, mtDNA content of lymphocytes without irradiation was found to be correlated to age. CONCLUSIONS mtDNA and CD content may be considered as predictive factors to radiation toxicity.