不同浓度卵蛋白变应原对小鼠哮喘模型建立的影响

目的研究不同浓度卵蛋白(ovalbumin,OVA)变应原对小鼠的哮喘造模影响。方法 96只6～8周龄SPF级雌性BALB/c小鼠随机分为8组,分别为PBS组(对照组)、10μg组(A组)、20μg组(B组)、50μg组(C组)、100μg组(D组)、200μg组(E组)、500μg组(F组)、1000μg组(G组)。A～G组分别用含1%明矾的PBS配制相应浓度的OVA于第0、7和第14天对小鼠进行腹腔注射。于第21～27天连续7 d用含1%的OVA的PBS溶液雾化吸入激发各组小鼠。正常对照组使用PBS溶液致敏和激发。最后一次雾化吸入激发后24 h内,计数各组小鼠支气管肺泡灌洗液(BLAF)中嗜酸性粒细胞的含量,ELISA法检测IL-4、IL-5的分泌量及其血清IgG2a、IgE抗体的水平;肺组织病理切片观察各组小鼠哮喘模型的效果,评价最优哮喘造模的OVA浓度。结果 A～G组小鼠肺泡灌洗液中IL-4、IL-5含量均高于正常对照组(P<0.01),细胞因子水平随着OVA浓度的增高而逐渐下降;A～G组小鼠肺泡灌洗液中嗜酸性粒细胞数均高于正常对照组(P<0.01),从低浓度组至高浓度组嗜酸性粒细胞数从高向低变化;A～G组小鼠血清中总抗体IgE的水平均显著高于正常对照组(P<0.01),且随着OVA浓度的增高IgE水平逐渐下降。血清中IgG2a的水平则随OVA给药浓度的增高而逐渐增高;低浓度OVA致敏组小鼠肺组织标本可观察到明显的炎症浸润性病理表现,而高浓度组肺部组织病理变化不明显。结论低浓度的OVA连续致敏小鼠造成过敏性哮喘病理改变较为明显,随着OVA浓度的增高,造模效果逐渐降低,而高浓度的OVA则会导致模型小鼠发生免疫耐受。

Effect of different doses of ovalbumin on the establishment of an asthmatic mouse model

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.Results All 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.Conclusions Low 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.