Monoclonal antibody (EGR/G49) reactive with the epidermal growth factor receptor of A431 cells recognizes the blood group ALeb and ALey structures.

The carbohydrate specificity of the monoclonal antibody EGR/G49, raised against the epidermal growth factor (EGF) receptor of A431 cells, has been investigated by assessing its interactions with glycoproteins and erythrocytes derived from individuals of known blood group ABH, Lewis and secretor types, and by inhibition of binding assays using structurally defined oligosaccharides. The results indicate that this antibody reacts with the difucosylated blood group structures ALeb and ALey: (formula; see text) This antibody differs from the previously described anti-EGF receptor antibody. TL5, which is directed at the terminal blood group A trisaccharide structure and reacts poorly with the ALeb/Ley structures. Since both antibodies were selected for their reactivities with the receptor for EGF, their specificities provide evidence for the presence of both the mono- and difucosylated blood group A structures on the receptor glycoprotein. These antibodies will be invaluable in the studies of the distribution and the roles of blood group related carbohydrate structures in the organisation and function of the EGF and other receptor systems.