Monoclonal antibody detects embryonic epitope specific for nerve‐derived transferrin

Abstract

Monoclonal antibodies were generated against transferrin purified from chick embryo extract by fusing spleen cells from BALB/c mice immunized against embryonic transferrin, with myeloma cells. Antibodies produced by the selected hybridoma clones were all type IgG. Twelve clones were selected for secretion of antibodies to the embryo extract-derived transferrin, and three clones were studied extensively. Immunoblotting was used to demonstrate antibody binding to several avian transferrin proteins derived from adult chicken serum, adult chicken peripheral nerves, and ovotransferrin. Screening and detailed epitope analysis were accomplished by solid-phase immunoassay. The results indicated that two clones, 2G9.1 and 2B11.1, recognized the embryonic and egg antigens in preference to the adult proteins. However, a third clone, 6H2.1, recognized the nerve-derived transferrin preferentially to both the embryonic and adult serum antigens. None of the clones recognized the serum-derived transferrin in preference to the other antigens. These results indicate that embryonic epitope(s) are conserved in the nerve- but not the serum-derived transferrin. They also show that the neural antigen has site(s) distinct from the embryonic proteins. No changes in displacement curves were observed after these proteins were digested with neuraminidase, indicating that the epitope differences discovered are not intimately related to sialic acid residues on the various transferrins.