Effect of Dose Rate on Residual [gamma]-H2AX Levels and Frequency of Micronuclei in X-Irradiated Mouse Lymphocytes

• Published in: Radiation research 2015-03, Vol.183 (3), p.315
• Main Authors: Turner, H C, Shuryak, I, Taveras, M, Bertucci, A, Perrier, J R, Chen, C, Elliston, C D, Johnson, G W, Smilenov, L B, Amundson, S A, Brenner, D J
• Format: Article
• Language: English
• Subjects: Irradiation; Lymphocytes; Risk assessment
• ISSN: 0033-7587; 1938-5404

This study aims to assess the risk related to DNA damage, and compare the yields of two established biodosimetry end points, γ-H2AX and micronuclei (MNi), in peripheral mouse blood lymphocytes after prolonged in vivo exposure to low-dose-rate (LDR) X rays vs. acute high-dose-rate exposure. C57BL/6 mice were total-body irradiated with 320 kVP X rays with doses of 0, 1.1, 2.2 and 4.45 Gy. Residual levels of total γ-H2AX fluorescence in lymphocytes isolated 24 h after the start of irradiation were assessed using indirect immunofluorescence methods. At the 4.45 Gy dose there was no difference in γ-H2AX expression between the two dose rates, whereas there was a two- to three-fold increase in apoptosis in the LDR samples compared to the equivalent 4.45 Gy acute dose. The results showed that MNi yields increased up to 2.2 Gy with no further increase at 4.45 Gy and with no detectable dose-rate effect across the dose range 24 h or 7 days post exposure.