The effect of vaccination with DNA encoding murine T-cell epitopes on the Der p 1 and 2 induced immunoglobulin E synthesis

Background: Immunization with naked plasmid DNA leads to strong and persist ent cell-mediated and humoral immune response to plasmid encoded antigen. V accination of DNA encoded whole allergen has been tried, but little informa tion is currently available on the efficacy of DNA encoding T-cell epitopes in allergic disease. The purpose of this study was to determine whether th e vaccination of naked plasmid DNA encoding only T-cell epitopes suppresses the allergic reaction as effectively as naked DNA encoding whole segments of allergen. Methods: We immunized mice with a mixed naked plasmid DNA encoding the five classes of murine T-cell epitopes on Der p I and Der p 2 three times at we ekly intervals via an intramuscular injection of BALB/c mice. Control mice were injected with the pcDNA 3.1 blank vector. After 3 weeks, the mice were actively sensitized twice and allowed to inhale the Der p extracts intrana sally six times at weekly intervals. Results: The vaccinated mice showed a significant attenuated induction of D er p-specific immunoglobulin E synthesis compared to controls. In terms of the Der p-specific IgG2a antibody response, the vaccinated mice showed more prominent responses than the control mice group. In addition, analysis of the cytokine profile after Der p stimulation of the lymph-node cells reveal ed that the level of the mRNA expression of the interferon-gamma gene was h igher in the vaccinated mice than in the controls. Histologic studies showe d a much reduced infiltration of inflammatory cells in lung tissue of the g ene-vaccinated mice in comparison with the controls. Conclusions: These results suggest that vaccination with DNA encoding T-cel l epitopes effectively inhibits allergen-induced IgE synthesis and reduces cell infiltration in lung tissue. Thus, gene therapy using T-cell epitope-e ncoding DNA presents an ideal way of combating allergic disease in the futu re.