Ultrastructural and immunohistochemical studies on food allergy and intestinal barrier system

在本研究中，我们试图阐明新生大鼠和哺乳大鼠空肠和回肠吸收细胞中变应原的内吞途径，以及变应原是否跨细胞运输。我们将大分子示踪剂应用于小肠腔内，并对吸收细胞进行光镜和电子显微镜观察，当以生理盐水冲洗肠腔后铝内注射包括卵白蛋白在内的示踪剂作为弱屏障系统模型时，在吸收细胞和细胞间隙中观察到的反应产物比未处理的小肠增加。提示当覆盖顶膜区表面的粘液减少时，非特异性大分子和食物过敏原如卵清蛋白容易侵入空肠上皮，进而侵入固有层，当HRP或IgA被注入血管时，它们被从基侧膜域内吞入小肠吸收细胞，并经细胞进入肠腔。我们的结果表明，吸收细胞中非特异性大分子和IgA的内吞途径在空肠和回肠之间不同，在哺乳动物和成年动物之间也不同。包括免疫球蛋白A在内的大分子细胞从基侧质膜区向顶端质膜的穿细胞性活跃。

In the present study, we attempted to elucidate the endocytic pathways of allergen in the jejunal and ileal absorptive cells of the neonatal and suckling rats in vivo, and whether allergen is transported across the cells. We applied macromolecule tracers to the small intestinal lumen, and examined the absorptive cells with light and electron microscopy.When tracer including ovalbumin was injected intraluminally after washed the lumen by saline as a weak barrier system model, reaction product that observed in the absorptive cells and intercellular space was increased as compared with non-treated small intestine. It is suggested that when mucus that covers the surface of the apical membrane domain decreases, non-specific macromolecules and food allergen as ovalbumin make easily an invasion into the epithelium of the jejunum and then into the lamina propria mucosae.When HRP or IgA was injected into the blood vessel, they were endocytosed into the small intestinal absorptive cells from the basolateral membrane domain, and transcytosed into the small intestinal lumen. Our results are suggested that endocytic pathways of non-specific macromolecule and IgA in the absorptive cells vary between jejunum and ileum, and also vary between suckling and adult animals. Transcytosis from basolateral plasma membrane domain to apical plasma membrane of macromolecules including IgA were occurred actively.