Radiation Dose-Rate Effects on Select Biomarkers in a Mouse Total-Body Irradiation Model

In the event of acute radiation exposure, absorbed dose may be unknown and biodosimetry tools are needed by first responders to properly triage patients. We evaluated two protein markers -FMS-related tyrosine kinase 3 ligand (Flt3L) and granulocyte colony-stimulating factor (G-CSF) -that are known to be elevated after an acute radiation exposure, as well as total white blood cell (WBC) count changes pre-and post-irradiation at different dose-rates. Female B6D2F1 mice were divided into one sham-irradiated control group and four total-body irradiated groups. Experimental groups received a total dose of 8 Gy of 60 Co gamma photon irradiation at four dose-rates: 0.04, 0.15, 0.30, and 0.47 Gy min -1 . Blood samples from mice were collected at 24 and 48 hours post-exposure for WBC and protein biomarkers (Flt3L and G-CSF). Flt3L values at all dose-rates except 0.15 were significantly elevated from controls but not each other. The G-CSF levels in mouse groups of 0.47 Gy min -1 and 0.04 Gy min -1 were significantly different from controls, and 0.15 Gy min-1 significantly differed from 0.47 Gy min -1 . WBC changes from baseline showed that all experimental groups were significantly lower than controls, and additionally the 0.04 Gy min -1 group was significantly lower than the 0.30 Gy min -1 group. Though more research is needed, it would appear that at the fixed dose, dose-rates, and time points chosen herein may not be particularly strong or show predictable differences in the selected biomarker expression levels.