The use of discriminant analysis for evaluation of early-response multiple biomarkers of radiation exposure using non-human primate 6-Gy whole-body radiation model

The present need to rapidly identify severely irradiated individuals in mass-casualty and population-monitoring scenarios prompted an evaluation of potential protein biomarkers to provide early diagnostic information after exposure. The level of specific proteins measured using immunodiagnostic technologies may be useful as protein biomarkers to provide early diagnostic information for acute radiation exposures. Herein we present results from on-going studies using a non-human primate (NHP) 6-Gy X-rays ( 0.13Gymin-1) whole-body radiation model. Protein targets were measured by enzyme-linked immunosorbent assay (ELISA) in blood plasma before, 1, and 2 days after exposure. Exposure of 10 NHPs to 6 Gy resulted in the up-regulation of plasma levels of (a) p21 WAF1/CIP1, (b) interleukin 6 (IL-6), (c) tissue enzyme salivary αα-amylase, and (d) C-reactive protein. Data presented show the potential utility of protein biomarkers selected from distinctly different pathways to detect radiation exposure. A correlation analysis demonstrated strong correlations among different combinations of four candidate radiation-responsive blood protein biomarkers. Data analyzed with use of multivariate discriminant analysis established very successful separation of NHP groups: 100% discrimination power for animals with correct classification for separation between groups before and 1 day after irradiation, and 95% discrimination power for separation between groups before and 2 days after irradiation. These results also demonstrate proof-in-concept that multiple protein biomarkers provide early diagnostic information to the medical community, along with classical biodosimetric methodologies, to effectively manage radiation casualty incidents.