PRETREATMENT WITH ALLERGEN PREVENTS IMMEDIATE HYPERSENSITIVITY AND AIRWAY HYPERRESPONSIVENESS

The ability of subcutaneous pretreatment with an immunogenic peptide d erived from Fel d I, the major cat protein, to suppress the developmen t of allergic responses was examined in a mouse model of antigen-induc ed sensitization. BALB/c mice exposed to aerosolized Fel d I chain 1 p eptide developed antigen-specific IgE responses, immediate cutaneous r eactivity to the peptide, and increased airway responsiveness (AR). Bo th subcutaneous and intraperitoneal administration of the peptide prio r to sensitization caused a 50% reduction in cutaneous reactivity whic h 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 injection s could prevent the development of increased AR. Transfer of spleen ce lls from subcutaneously peptide-treated mice to sensitized recipients reduced serum antigen-specific IgE and IgG1 antibody responses and ski n test reactivity, and prevented alterations in AR. These data suggest that IgE (and lgG1) responses and airway hyperresponsiveness induced by allergen sensitization via the airways can be modulated by subcutan eous administration of peptide. Further, the results define a model fo r investigating the modulatory effects of subcutaneous administration of immunogenic peptides or protein on an ongoing allergic response.