Induction of immune recognition of self-epidermal growth factor II: Characterization of the antibody response and the use of a fusion protein

The characteristics of the antibody immune response against self-epidermal growth factor (EGF) were studied in mice and monkeys immunized with EGF linked to different carrier proteins and in different adjuvants. Mice produced anti-EGF antibodies mainly of the IgG1 subclass, and higher responses were obtained when Montanide ISA 51 or Freund's adjuvant was used and when using the intramuscular route of administration. Monkeys immunized with human recombinant EGF (Hu-EGF) linked to a carrier protein produced antibodies that blocked binding between EGF and its receptor (EGF-R). The increase in the inhibition capacity of sera was not directly related to an increase in antibody titers. The relationship between antibody titers and survival of Ehrlich ascites tumor (EAT)-bearing mice was demonstrated in NMRI-immunized animals. The possibility of the P64k recombinant protein from Neisseria meningitidis being used as carrier protein was studied in mice and monkeys. A fusion protein that contains the Hu-EGF sequence inserted between amino acids 45/46 of P64k was constructed and, when used as an immunogen in mice, elicited anti-EGF antibody responses and an increase in survival of immunized animals transplanted with EAT cells.