Prophylactic and therapeutic intervention in IgE responses by biolistic DNA vaccination primarily targeting dendritic cells

Background

Allergen gene transfer represents an alternative approach to specific immunotherapy with allergen extracts. Gene gun–mediated DNA immunization with plasmid vectors expressing a transgene under control of the promoter of the fascin gene (pFascin) allows for antigen production predominantly by dendritic cells and resulted in the generation of CD8⁺ cytotoxic T lymphocytes as well as in the development of a type 1 immune response.

Objective

We compared the in vivo efficiency of biolistic transfection with pFascin and plasmids containing the cytomegalovirus promoter (pCMV) in a mouse model of type I allergy.

Methods

BALB/c mice were sensitized with the model allergen β-galactosidase to induce a distinctive type 2 immune response. The effect of prophylactic as well as therapeutic biolistic transfection with β-galactosidase–encoding plasmids on the development of antibody titers was followed, and anaphylactic potential of sera was determined. Spleen cells were stimulated in vitro to analyze cytokine production and induction of CD8⁺ effector T cells.

Results

Protective allergen gene transfer with pFascin efficiently prevented specific IgE production accompanied by immune deviation toward a T_H1-polarized immune response as well as by the induction of IFN-γ–producing CD8⁺ effector T cells, being comparable to vaccination with pCMV. In a therapeutical setting, biolistic DNA vaccination with pFascin or pCMV transiently protected allergen-sensitized mice against the strong increase in specific IgE production caused by subsequent allergen challenge.

Conclusion

We demonstrate for the first time that restricting transgene expression primarily to dendritic cells after DNA vaccination suffices to cause inhibition of IgE production prophylactically and therapeutically.

Key words: Immunoglobulin E, type I allergy, allergen gene transfer, gene gun–mediated DNA vaccination, dendritic cells, fascin, mouse, β-galactosidase

Abbreviations used: alum, Aluminium hydroxide, APC, Antigen-presenting cell, βGal, β-Galactosidase, CTL, Cytotoxic T lymphocyte, DC, Dendritic cell, EGFP, Enhanced green fluorescent protein, LN, Lymph node, pCMV, Plasmid vector harboring the cytomegalovirus promoter, pFascin, Plasmid vector harboring the murine fascin promoter, RBL, Rat basophil leukemia