Abstract
There is a crucial shortage of methods capable of determining the extent of accidental exposures of human beings to ionizing radiation. However, knowledge of individual exposures is essential for early triage during radiological incidents to provide optimum possible life-sparing medical procedures to each person.
We evaluated an immunocytofluorescence-based quantitation of gamma-H2AX foci as a biodosimeter of total-body radiation exposure (60Co gamma-rays) in a rhesus macaque (Macaca mulatta) model. Peripheral blood lymphocytes and plucked hairs were collected from 4 cohorts of macaques receiving total body irradiation (TBI) doses ranging from 1 Gy to 8.5 Gy. Each cohort consisted of 6 experimental and 2 control animals. Numbers of residual gamma-H2AX foci were proportional to initial irradiation doses and statistically significant responses were obtained until 1 day after 1 Gy, 4 days after 3.5 and 6.5 Gy, and 14 days after 8.5 Gy in lymphocytes and until 1 day after 1 Gy, at least 2 days after 3.5 and 6.5 Gy, and 9 days after 8.5 Gy in plucked hairs.
Based on data obtained from the TBI study we introduce a partial-body irradiation (PBI) exposure analysis method. We established standard curves for PBI using Qgamma-H2AX (mean number of gamma-H2AX foci per damaged cell) and Fgamma-H2AX (fraction of damaged cells).
Our findings indicate that quantitation of gamma-H2AX foci may make a robust biodosimeter for analyzing exposure to ionizing radiation in humans and could help clinicians prescribe appropriate types of medical intervention for optimal individual outcome.
This research was supported by the NIAID Radiation/Nuclear Countermeasures Program, the Intramural Research Program of the National Cancer Institute, Center for Cancer Research, NIH and the Armed Forces Radiobiology Research Institute under research work unit number BD-13 (RBB4AR).
