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 CD(11c)(+)CD(80)(+ )and CD(11c)(+)CD(86)(+ )co-stimulatory molecules in spleen dendritic cells (DCs), circulating CD(4)(+ )and CD(8)(+ )T cells, Foxp3(+ )in spleen CD(4)(+ )T cells and spleen CD(4)(+ )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 CD(4)(+)and CD(8)(+ )T cells and the number of spleen Foxp(3)(+ )Treg. Those changes with increased INF-γ 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.