Ultrastructural and immunohistochemical studies on food allergy and intestinal barrier system

在本研究中，我们试图阐明过敏原在新生和哺乳大鼠空肠和回肠吸收细胞中的内吞途径，以及过敏原是否在细胞间转运。我们将大分子示踪剂应用于小肠腔内，用光镜和电镜观察吸收细胞。将含卵清蛋白的示踪剂作为弱屏障系统模型，经生理盐水冲洗后注入腔内，与未处理的小肠相比，吸收细胞和细胞间隙中观察到的反应产物增加。提示当覆盖顶膜域表面的黏液减少时，非特异性大分子和卵清蛋白等食物过敏原很容易侵入空肠上皮，进而进入固有层粘膜。将HRP或IgA注入血管后，由基底外侧膜域内吞入小肠吸收细胞，经转胞切进入小肠管腔。我们的研究结果表明，吸收细胞的非特异性大分子和IgA的内吞途径在空肠和回肠之间存在差异，在哺乳动物和成年动物之间也存在差异。包括IgA在内的大分子从基底外侧质膜域向根尖质膜的胞吞作用活跃。

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.