Pretreatment with allergen prevents immediate hypersensitivity and airway hyperresponsiveness.

The ability of subcutaneous pretreatment with an immunogenic peptide derived from Fel d I, the major cat protein, to suppress the development of allergic responses was examined in a mouse model of antigen-induced sensitization. BALB/c mice exposed to aerosolized Fel d I chain 1 peptide developed antigen-specific IgE responses, immediate cutaneous reactivity to the peptide, and increased airway responsiveness (AR). Both subcutaneous and intraperitoneal administration of the peptide prior to sensitization caused a 50% reduction in cutaneous reactivity which was associated with a decrease in serum anti-Fel d I chain 1 IgE and IgG1 antibody responses and an increase in specific IgG. Pretreatment with the peptide also suppressed spleen and lymph node proliferative responses to the peptide. However, only subcutaneous peptide injections could prevent the development of increased AR. Transfer of spleen cells from subcutaneously peptide-treated mice to sensitized recipients reduced serum antigen-specific IgE and IgG1 antibody responses and skin test reactivity, and prevented alterations in AR. These data suggest that IgE (and IgG1) responses and airway hyperresponsiveness induced by allergen sensitization via the airways can be modulated by subcutaneous administration of peptide. Further, the results define a model for investigating the modulatory effects of subcutaneous administration of immunogenic peptides or protein on an ongoing allergic response.