Monoclonal antibodies against the human epidermal growth factor receptor from A431 cells. Isolation, characterization, and use in the purification of active epidermal growth factor receptor.

A431 cells have been used as an immunogen for generating monoclonal antibodies against the epidermal growth factor (EGF) receptor. Two immunoglobulin M and eight immunoglobulin G3 anti-EGF receptor antibodies were cloned. All ten antibodies immunoprecipitated biosynthetically labeled mature A431 cell EGF receptor and were able to recognize the receptor in Western blotting. However, none of the antibodies immunoprecipitated precursor polypeptides of the A431 cell EGF receptor, neither did they recognize EGF receptors from human foreskin fibroblasts, human placenta, nor a human-mouse hybrid cell expressing EGF receptor. The antibodies were found to bind to glycolipids from A431 cells and it was shown that the determinant involved was the blood group A antigen. It appears that this determinant is present on both the EGF receptor and glycolipids of A431 cells but is not expressed on EGF receptors from other human cells tested. One of the monoclonal antibodies raised was used for immunoaffinity purification of the EGF receptor. The procedure took advantage of the carbohydrate nature of the antigenic determinant by employing sugar-specific elution. The mild conditions permitted the purification of A431 cell EGF receptor (70-80% pure) that possessed an intrinsic EGF-stimulated tyrosine kinase activity with a specific activity of about 20 nmol/min/mg.