Objective      To establish a mouse model of immune tolerance of asthma through subcutaneous injection with high dose of ovalbumin (OVA) in the abdomen and investigate its underlying mechanism.       Methods      With a random number table method

18 female BALB/c mice were divided into 3 groups: asthmatic immune tolerance model group

asthma control group and normal control group

with 6 mice in each group. The mice in the model group and asthma control group were sensitized with 10 μg OVA by intraperitoneal injection in the abdomen on day 0 and day 7. The mice in the model group induced immune tolerance with 1 mg OVA by subcutaneous injection in the abdomen everyday from day 21 to day 25. Both the model group and asthma control group were challenged with 1% OVA on day 35

day 36 and day 37. The mice in the normal control group was sensitized and challenged with the equal amount of saline. The airway reactivity was detected at 24 h after the last challenge. The enhanced pause (Penh) was measured to evaluate the airway responsiveness with a noninvasive lung functional instrument. Bronchoalveolar lavage fluid (BALF) was collected to count the total cells and eosinophils

and the cytological studies were conducted. The OVA-specific IgE in peripheral blood

and the IL-4

IFN-γ and IL-10 in BALF were detected by enzyme-linked immunosorbent assay (ELISA). The lung tissues were obtained to perform histological analysis by HE staining. The percentage of regulatory T cells in peripheral blood was calculated by flow cytometry.       Results      The airway responsiveness

total cells and eosinophils in BALF of the model group were significantly decreased as compared with the asthma control group (P0.05). The OVA-specific IgE in peripheral blood and IL-4 in BALF were significantly lower in the model group than that in the asthma control group (P0.05)

and on the contrary

the levels of IL-10 were significantly higher (P0.05). The levels of IFN-γ had no significant difference. The inflammation of lung tissues was alleviated in the model group. The percentage of regulatory T cells in the model group was significantly higher than that in the asthma control group (P0.05).       Conclusion      Subcutaneous injection with high dose of OVA can establish the mouse model of asthmatic immune tolerance successfully

which can provide a foundation for further researching the mechanism of asthmatic immune tolerance. Regulatory T cells and IL-10 immunosuppressive factors are involved in the immune tolerance.