Antibody responses to bee melittin (Api m 4) and hornet antigen 5 (Dol m 5) in mice treated with the dominant T-cell epitope peptides

Background: Mice treated with the dominant T-cell epitope peptides of allergens were reported to have reduced peptide- or allergen-specific T-cell responses on subsequent immunization, but the extent of reduction of allergen-specific antibodies is not clear. Objective: This study was done to compare the extent of reduction of T-cell and antibody responses in peptide-treated mice. Two allergens were tested. Bee melittin (Api m 4), an allergen of 26 amino acid residues, has a single dominant Tor B-cell epitope. Hornet antigen 5 (Dol m 5), an allergen of 204 amino acid residues, has multiple dominant T- or B-cell epitopes. Methods: Mice were treated with T-cell peptides of Api m 4 or Dol m 5 and then immunized biweekly with their respective allergen with alum adjuvant. T-cell peptides tested were residues 7-19 of Api m 4 and residues 41-60, 141-160, and 176-195 of Dol m 5. T-cell responses at week 9 or 11 were assayed by proliferation of spleen cell cultures. Antibody responses of different isotypes were measured biweekly by ELISA. Results: Partial reduction of 30% to 50% of T-cell responses to peptide or allergen was observed in bee and hornet peptide-treated mice. About 65% reduction of Api m 4-specific antibody response was observed early in the immune response but gradually subsided to about 40% late in the response. Partial reduction of about 40% of Dol m 5-specific antibody response was only observed early in the immune response. Conclusion: Peptide treatment is partially effective in the reduction of T-cell responses of univalent or multivalent allergens. It is also partially effective in the reduction of antibody response of a univalent allergen, but it is poorly effective for a multivalent allergen.