Protection against the allergic airway inflammation depends on the modulation of spleen dendritic cell function and induction of regulatory T cells in mice

BACKGROUND Allergen-induced imbalance of specific T regulatory (Treg) cells and T helper 2 cells plays a decisive role in the development of immune response against allergens. OBJECTIVE To evaluate effects and potential mechanisms of DNA vaccine containing ovalbumin (OVA) and Fc fusion on allergic airway inflammation. METHODS Bronchoalveolar lavage (BAL) levels of inflammatory mediators and leukocyte infiltration, expression of CD11c+CD80+ and CD11c+CD86+ co-stimulatory molecules in spleen dendritic cells (DCs), circulating CD4+ and CD8+ T cells, Foxp3+ in spleen CD4+ T cells and spleen CD4+ T cells were measured in OVA-sensitized and challenged animals pretreated with pcDNA, OVA-pcDNA, Fc-pcDNA, and OVA-Fc-pcDNA. RESULTS OVA-Sensitized and challenged mice developed airway inflammation and Th2 responses, and decreased the proliferation of peripheral CD4+and CD8+ T cells and the number of spleen Foxp3+ Treg. Those changes with increased INF-gamma production and reduced OVA-specific IgE production were protected by the pretreatment with OVA-Fc-pcDNA. CONCLUSION DNA vaccine encoding both Fc and OVA showed more effective than DNA vaccine encoding Fc or OVA alone, through the balance of DCs and Treg.