High-throughput antibody-based assays to identify and quantify radiation-responsive protein biomarkers

PURPOSE: After a radiological 'dirty bomb' incident in a major metropolitan center, substantial numbers of people may be exposed to radiation. However, only a fraction of those individuals will need urgent medical attention. Consequently, a rapid screening test is needed to identify those people who require immediate treatment. MATERIAL AND METHODS: Ten normal human cell lines were screened by enzyme-linked immunosorbent assay (ELISA) for the expression of a dozen secreted cytokines that have been reported to have changes in protein or mRNA levels at 1, 2, and 3 days after 0-10 Gy irradiation using (137)Cs gamma rays at 0.82 Gy min(-1). After this systematic in vitro screen, we measured changes in the level of a subset of these candidate proteins in plasma from irradiated C57BL/6 mice (n = 3 per group), comparing shams with a single radiation dose (5 Gy X-rays) at 3.7 Gy min(-1) at 6 h after irradiation. RESULTS: We identified four cytokine molecules that had altered levels after radiation exposure, one of which, Interleukin (IL) 6, was consistently elevated after irradiation in vitro and in vivo. CONCLUSIONS: Our findings underscore the potential for IL6 as a marker for an immunoassay-based, rapid, high-throughput biodosimeter.