Objective To explore the effect of plasmid DNA vaccines encoding the major allergens of house dust mite

der p1 and der p2

on the functions of Foxp3

+

regulatory T cells (Treg cells) of mouse asthma model.  Methods Totally 16 C57BL/6J mice were sensitized and challenged with standard house dust mite extract solution to establish asthma model

and another 8 mice receiving PBS instead of extract solution served as normal control. The 8 asthma mice of treatment group were immunized with the plasmid mixture (pDs-Der p1 and pCI-neo-Der p2 in 1∶1)

while those in asthma group were given PBS injection. Twenty-four hours after re-challenged

the mice were killed and their spleen CD4

+

T cells were isolated and collected. The proportion of CD25

+

Foxp3

+

T cells in the CD4

+

T cells were determined with flow cytometry. Spleen CD4

+

CD25

+

T cells were obtained by magnetic activated cell sorting and flow cytometry. After cultured with IL-2

the proliferation of CD4

+

CD25

+

T cells was examined by scintillation counting. After cultured with CD4

+

CD25

+

T cells and house dust mite extract

the proliferation of CD4

+

CD25

-

T cells was measured

and the supernatants were harvested to measure IL-4

IL-5 and IFN-γ.  Results The number and proportion of CD4

+

CD25

+

Foxp3

+

T cells were higher in control and treatment groups than in the asthmatic group. The expansion of CD4

+

CD25

+

Foxp3

+

T cells was low in the 3 groups

and their secretion of IL-10 and TGF-β were undetectable. The CD4

+

CD25

+

Foxp3

+

T cells from the 3 groups inhibited expansion of CD4

+

CD25

-

T cells and their secretions of IL-4

IL-5 and IFN-γ

but the cells from asthmatic mouse had lesser efficiency.  Conclusion Foxp3

+

regulatory T cells efficiently inhibit the function of CD4

+

CD25

-

T cells. Both the number and the cytokine secretion of Foxp3 regulatory T cells are decreased in asthmatic mouse

allergen DNA vaccines interfere the number and the cytokine secretion.