Production of monoclonal antibodies with specificity for different epitopes on the human epidermal growth factor molecule.

Four different monoclonal antibodies (MAbs) to human epidermal growth factor (hEGF) were obtained from mouse hybridoma cell lines. They were highly specific for hEGF and did not cross-react appreciably with mouse EGF. The immunoglobulin class of these MAbs was IgG1 or IgG2a. The apparent Kd values for hEGF of these MAbs ranged from 10(-10) to 10(-9) M. These MAbs all inhibited DNA synthesis in BALB/c3T3 cells stimulated by hEGF and 125I-labeled hEGF binding to the receptor of the cells. Reduction of hEGF with dithiothreitol decreased its reactivity with these MAbs, suggesting that they recognized the conformation of the hEGF molecule maintained by the three disulfide bonds. By competitive binding experiments with hEGF, these four MAbs were classified into three groups: two binding to an A domain of hEGF, one to a B domain, and one to a C domain and preventing the bindings of the other MAbs at the A and B domains. When a methionyl residue of hEGF was removed by its treatment with CNBr, the immunological reactivity of the C domain, but not the A or B domain, was destroyed in association with a decrease in the biological activity of the growth factor. These MAbs should be useful in studies on the structure-function relationship of hEGF.