早期接触过敏原对大鼠哮喘模型的影响

Effect of early exposue to allergen on rat asthmatic model

目的:了解早期接触卵蛋白(ovalbumin,OVA]对大鼠哮喘模型的影响。方法:将新生SD大鼠随机分为阴性对照组、哮喘模型组、小剂量组和大剂量组,每组8只,其中小剂量组和大剂量组大鼠于生后当天分别一次性注射2g／L OVA 0．1 mL和10g／L OVA 0．1 mL。6周后,哮喘模型组、小剂量组和大剂量组经OVA致敏并制作哮喘模型。分别观察各组大鼠肺组织病理、支气管肺泡灌洗液(bronchoalveolar lavage fluid,BALF)中细胞计数和分类、外周血白细胞介素-4(interleukin-4,IL-4)、γ-干扰素(interferon-γ,IFN-γ)、OVA-IgE和OVA-IgG水平。结果:小剂量组和大剂量组肺组织病理显示气道炎症较哮喘组明显减轻,BALF中细胞总数、中性粒细胞和嗜酸性粒细胞比例较哮喘组显著下降,两组大鼠血IL-4和OVA-IgE较哮喘模型组显著下降,IFN-γ水平则较哮喘模型组显著增加。大剂量组与对照组比较,IL4和IFN-γ及OVA-IgE差异无统计学意义。哮喘模型组、小剂量组和大剂量组大鼠血 OVA-IgG较对照组显著增加,且大剂量组较哮喘组显著增加。结论:出生后早期接触OVA可抑制大鼠成年后OVA 所诱发的气道炎症改变和特异性IgE增加,其机制可能与诱导免疫耐受形成有关。

Objective： To investigate the effect of early exposure to allergen（ovalbumin,OVA） on rat asthmatic models. Methods： Neonate rats were randomly divided into negative control group, asthmatic model group, low dose group and high dose group, with 8 in each. The rats of low dose group and high dose group were injected subcutaneously with 2 g/L OVA 0.1 mL and 10 g/L OVA 0.1 mL separately on the 1 st day. OVA was given in asthmatic model group, low dose group and high dose group for allerginizing 6 weeks later and then asthmatic models were made. The pathologic changes of lung tissue, cell count and differentiation of bronchoalveolar lavage fluid （BALF） and serum interleukin-4 （IL-4）, interferon-γ/（IFN- γ）,OVA-specific IgE and OVA- specific IgG were observed. Results： The airway inflammation in both low dose group and high dose group was less severe than that in asthmatic modol group. Total cell count of BALF and the ratio of eosinophil and neutrophil of both groups were decreased significandy compared with asthmatic model group. IL-4 and OVA-specific IgE were markedly decreased, while IFN-γ was significantly increased in both low dose group and high dose group compared with asthmatic model group respectively. There was no significant difference in IL-4, IFN-γ and OVA-specific IgE between high dose group and control group. The serum OVA-specific IgG was elevated significantly in asthmatic model group, low dose group and high dose group compared with control group , and it was higher in high dose group than in asthmatic model group. Conclusion： Early exposure to OVA after birth could inhibit the airway intiammation and OVA-specific IgE increasing induced by OVA in grown-up rats, and the mechanisms might be related to formation of immunology tolerance.