Fluorometric enzyme immunoassay of basic fibroblast growth factor with monoclonal antibodies.

We compared three different strategies for measuring basic fibroblast growth factor (bFGF) by fluorometric enzyme immunoassay (EIA). After optimizing conditions, we found that a primary anti-bFGF MAb directly conjugated with peroxidase gave the best detection limit for recombinant bFGF (approximately 30 ng/L, 3 pg/assay tube) in a two-site sandwich assay. The detection limit of methods based on biotinylated primary MAbs or on secondary antibodies followed by streptavidin-conjugated peroxidase was slightly lower than that of the above method. Using the most sensitive EIA examined in this study, we made a preliminary measurement of immunoreactive bFGF in sera of apparently healthy people and found it to be 190 (SD 32) ng/L (n = 48), in agreement with an earlier reported value (30-206 ng/L). Also, the concentration of immunoreactive bFGF in sera was above normal in 19 of 31 patients with stomach cancer.