OBJECTIVETo investigate the effect of early allergen exposure on later development of allergic rhinitis in mouse.

METHODSTwenty-four BALB/c neonates were randomly divided into 4 groups (low-dose group, high-dose group, negative control group and positive control group), each group had 6 mice. The mice were administered ovalbumin (OVA) by subcutaneous injection on day 1, 5, 12 after birth (10 μg OVA in 0.05 ml saline for low-dose group, 1000 μg OVA in 0.05 ml saline for high-dose group, only saline for negative and positive control group). Then the mice were sensitized and intranasally challenged with OVA (saline without OVA was used in negative control group) after 6 weeks. Symptoms, histopathological changes of nasal mucosa were observed, OVA-IgE in serum was examined, cytokines IL-4, IL-5 and IFN-gamma were detected in the supernatant of cultured splenic mononuclear cells.

RESULTSCompared to the positive control group, symptoms and nasal mucosa histological changes of high-dose group was indistinctive. The level of OVA-IgE and cytokines IL-4, IL-5 (x(-) +/- s) in high-dose group [(265.11 +/- 26.29), (446.39 +/- 72.83) and (171.24 +/- 15.66) pg/ml, respectively] were significantly lower than those in positive control group [(665.85 +/- 43.15), (1113.45 +/- 30.47), (255.36 +/- 30.96) pg/ml, respectively, t value were 0.000, 0.000 and 0.009, respectively, all P < 0.05]. The level of IFN-γ in high-dose group [(319.74 +/- 56.30) pg/ml] was significantly higher than those in positive control group [(170.02 +/- 14.50) pg/ml, t = 0.000, P < 0.05]. There was no significant difference of the results between the low-dose group and positive control group.

CONCLUSIONSNeonatal immunization with high-dose OVA inhibited the future allergic rhinitis symptoms, nasal histological changes, serum OVA-IgE levels and Th1/Th2 cytokine imbalance, resulting in the protective effect.