Objective To examine the effect of different doses of ovalbumin (OVA) on the establishment of an asthmatic mouse model. Methods Ninety-six female specific pathogen-free(SPF)mice in the age of 6 to 8 weeks, were randomly divided into 8 groups:PBS (Controls), 10 μg (A), 20 μg (B), 50 μg (C), 100 μg (D), 200 μg (E), 500 μg (F), and 1000 μg (G) OVA groups. Increasing doses of OVA solution dispensed in PBS containing 1% alum was intraperitoneally injected into the mice exposed to the allergen on days 0,7 and 14, respectively, and the mice were challenged with aerosol inhalation of PBS containing 1% OVA for 7 consecutive days from the 21st to 27th day of intervention. PBS instead of OVA was used for sensitizing and challenging the mice in the control group. Twenty-four hours after the final inhalation and challenge, all the mice were sacrificed for determining the concentration of eosinophils in the bronchoalveolar lavage fluid (BALF), secretory contents of cytokine IL-4 and IL-5, and serum level of antibody IgG2a and IgE by enzyme linked immunosorbent assay (ELISA). Lung tissue samples were taken for pathological assessment of the asthmatic changes and to determine the optimal OVA dose for asthma modeling. ResultsAll the levels of IL-4 and IL-5 in the groups A to G were significantly higher than that of the controls (P<0.01). The level of cytokines was decreased with increasing OVA doses. The eosinophil counts were significantly higher in the groups A to G as compared with that of the control group (P<0.01), and the eosinophil counts were in inverse proportion to the dosage from low to high administration of OVA. Overall serum levels of antibody IgE were significantly elevated in the mice exposed to the allergen in proportion to the controls (P<0.01), and IgE levels were decreased with increasing doses of OVA. The IgG2a titer was increased with increasing doses of OVA. Inflammatory cell infiltration was observed evidently in the pulmonary tissues of the mice exposed to low dose of OVA, yet the pathological changes were not so distinct in the mice receiving high doses of OVA. ConclusionsLow dose of OVA by progressive exposure may result in significant pathological changes in mice with allergic asthma, and that the quality of the established animal models is declined with increasing dosage of OVA. High doses of OVA can lead to immune tolerance in the sensitization protocols.