Abstract
Purpose: In contrast to high-dose therapeutic irradiation, definitive research detailing the physiological effects of low-dose irradiation is limited. Notably, the immunological response elicited after low-dose irradiation remains controversial.
Materials and methods: Female C57BL/6 mice were whole- body-irradiated with a single or three daily fractions up to a total dose of 0.1, 1, or 10 cGy. Blood and spleen were harvested 2, 7 and 14 days after irradiation.
Results: The splenic CD4+ T cell subpopulations were temporarily increased at 2 days after single or fractionated irradiation, whereas the percentage of dendritic cells (DC) and macrophages was decreased. Whereas CD8+ T cell populations were decreased in single-dose irradiated mice at day 7, early and sustained reduction of CD8+ T cell numbers was observed in fractionated- dose-irradiated mice from day 2 until day 14. In addition, single-dose irradiation resulted in a Th1 cytokine expression profile, whereas fractionated-dose irradiation drove a Th2 shift. Additionally, increased expression of immune-related factors was observed at early time-points with single-dose irradiation, in contrast to the dose-independent induction following fractionated-dose irradiation.
Conclusions: Our results demonstrate that low-dose irradiation modulates the immune response in mice, where the sensitivity and kinetics of the induced response vary according to the dosing method.
Acknowledgements
This work was supported by the Nuclear Research & Development Program (NRF-2013M2A2A7028423) of the National Research Foundation of Korea and by Grant No. 20131610101840 from the Ministry of Trade, Industry & Energy. This study was also partially supported by a grant of the RTR 50457-2014, Korea Institute of Radiological & Medical Sciences.
Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.