Immunogenicity Studies with Haptenated Melittin Peptides: Implication for Membrane Involvement during the Recognition Step

Melittin peptides carrying 2,4‐dinitro‐6‐carboxyphenyl (Dncp) haptenic groups regularly evoked anti‐hapten IgG responses in mice or guinea pigs when the hapten was C‐terminally attached. Single haptens on the N‐terminal helix in several positions gave poor or no responses in the early stages but adequate titres after prolonged immunization. Peptides with Dncp at the C‐terminus as an invariant feature and a second Dncp in various positions along the peptide chain did not fail to produce adequate responses. The hampering effect is not due to a defect at the T‐cell level but involves the recognition step on the B‐cell. It is implied that the haptenic interaction with the paratope of the recognizing immunoglob ulin on the B‐cell involves the cell membrane in an important way. It is also suggested that late antibody responses should not be overlooked during the development of proteinaceous immunogens for vaccination.