Vaccination with DNA encoding human T-cell epitopes suppresses Der p induced allergic responses in mice.

The apparent complexity of allergen-specific T-cell response in terms of epitope usage in humans is a potential barrier to peptide-based immunotherapy for allergy. A knowledge of cross-reacting T-cell epitopes of common allergens might have an impact on the development of vaccines for immunotherapy. We examined the efficiency of vaccinating with plasmid DNA coding only human T-cell epitopes on the suppression of allergic reactions in mice. BALB/c mice that received an injection of mixed naked DNA plasmids encoding the five classes of human T-cell epitopes on Der p 1 and Der p 2 produced a significant reduction in total and Der p-specific immunoglobulin E (IgE) synthesis. In Der p specific-IgG2a antibody responses, vaccinated mice showed more prominent responses than controls. Higher levels of interferon-gamma, a Th1 cytokine associated with the suppression of IgE production, were found in the sera of vaccinated mice. Histologic studies showed a marked reduction in the infiltration of inflammatory cells in the lung tissues of vaccinated mice vs. controls. These results suggest that vaccination with DNA encoding human T-cell epitopes effectively inhibits allergic responses in mice and might induce cross-regulation on helper T-cell level in vivo.