Development of a Competitive Radioimmunoassay for Human Plasma Fibronectin

Abstract
A competitive radioimmunoassay (CRIA) for quantitating human plasma fibronectin levels has been developed and compared with a conventional immunoturbidimetry assay (IMTA). The assay ranges for CRIA and IMTA were 0.05–5 μg/ml and 100–1,000 μg/ml, respectively, and the lowest detectable amounts of fibronectin that differed significantly from zero were 17.6 ng and 50 μg. The correlation coefficient between CRIA and IMTA was r = 0.953 (p <0.001). We consider the CRIA as potentially useful in the identification and study of fibronectin in certain biological fluids where it may be present in low concentrations.