Enzyme-linked immunosorbent assay (ELISA) for human epidermal growth factor (hEGF)

An enzyme-linked immunosorbent assay for human epidermal growth factor (hEGF) by the sandwich method with the use of orthophenylene diamine (OPDA) for the substrate of the enzyme reaction was developed. This assay showed high sensitivity, and there was no problem with the recovery rates even without any pretreatment of samples. The changes of hEGF levels in plasma and serum depend on the condition of blood storage from sampling until separation of the cell content. The levels of hEGF markedly increased with time in serum, especially when stored at room temperature but less so in plasma. Changes of hEGF levels in plasma were negligible for up to 3 h if the blood was stored at 4 degrees C until separation.