A stable, sensitive assay for human fibronectin.

A solid-phase radioimmunoassay system to quantitate human fibronectin has been developed. This assay utilizes 125I-labeled affinity purified IgG directed against human plasma fibronectin. The sensitivity of this system is comparable to conventional (labeled antigen) radioimmunoassays having a detection limit of approximately 0.5 ng. This assay is relatively rapid (less than 24 h), the reagents are stable at 4 degrees C (less than 2 months), and the reproducibility is excellent. Both human plasma and cellular fibronectin react equivalently in this assay.