REASSESSMENT OF THE 2-SITE ENZYME-IMMUNOASSAY FOR HUMAN EPIDERMAL GROWTH-FACTOR (HEGF) AND MEASUREMENT OF IMMUNOREACTIVE HEGF IN HUMAN SERA AND URINE

We reassessed the enzyme immunoassay (EIA) system for hEGF previously developed by our laboratory (Clin Chim Acta 156:51-60, 1985), since it appeared that the reported EIA system detected not only hEGF but also pS2 protein owing to minor contamination by pS2 protein in the hEGF sample used for immunization. In this study, we purified the hEGF sample using Benzamidine-Sepharose 6B column chromatography as a critical step for purification and newly developed an EIA system with specificity for hEGF. We also measured the hEGF level in serum, plasma, and urine from normal subjects by our new EIA system and found that the values measured by the previous system were 1.2-5.8-fold higher than the new system values. These results suggest that the previous system detected ''hEGF'' in excess owing to the nonspecificity of the antibody used. We investigated the molecular nature of immunoreactive hEGF detected in serum using our new system and confirmed that considerable amounts of immunoreactive hEGF exist as a high molecular weight form through S-S linkage with some macromolecule(s) in human blood as reported previously (Biochem Int 12:677-683, 1986). (C) 1995 Wiley-Liss, Inc.