| 特集名 | 消化管と免疫 --最近の話題 | |
|---|---|---|
| 題名 | 腸管免疫の特殊性 (2) 生理機能的面から | |
| 発刊年月 | 2000年 03月 | |
| 著者 | 嵐 方之 | 札幌医科大学内科学第一講座 |
| 【 要旨 】 | 消化管には，その環境に特殊化して発達した免疫機構が存在する．B細胞やT細胞は，免疫誘導部位であるGALTで抗原刺激を受けて分化を開始する．B細胞はヘルパーT細胞が分泌する各種サイトカインの影響下でIgA産生細胞へと分化し，血流を介して粘膜固有層に再分布する．粘膜固有層や粘膜上皮層はエフェクター部位として機能する．形質細胞により産生されたIgAは，腸管上皮細胞を介して腸管腔内に分泌型IgAとして分泌される．腸管上皮細胞は，細胞表面分子の発現やサイトカインの分泌により粘膜の炎症細胞やリンパ球との間で互いの機能を調節している．また，上皮細胞間リンパ球に対し非古典的class I分子を介して抗原提示を行っている可能性がある． | |
| Theme | Mucosal Immune System of the Digestive Tract -- Recent Topics | |
|---|---|---|
| Title | Functional Aspects of the Cells in Gut Immune System | |
| Author | Masayuki Arashi | Department of Internal Medicine(Section 1) Faculty of Medicine, Sapporo Medical College |
| [ Summary ] | Gut immune system has been developed in environments where the mucosal surface was exposed to an enormous amount of foreign antigens such as pathogenic microorganisms. Gut-associated lymphoid tissues(GALT) such as the Peyer's patches, are known to be inductive sites for mucosal immunity, where B cells and T cells are stimulated by luminal antigens and initiate their differentiation. Various cytokines secreted by helper T cells induce B cell differentiation to IgA producing cells. After migrating into the circulatory system, these cells repopulate the effector sites, the mucosal lamina propria and the epithelium. Locally produced IgA is transported through intestinal epithelial cells(IECs) and secreted into the gut lumen in the form of secretory IgA (SIgA). IEC could regulate the functions of inflammatory cells and lymphocytes in the lamina propria and the epithelial layer, via a wide variety of surface molecules and cytokines, and the vise versa. Furthermore, IECs could act as APCs for intraepithelial lymphocytes (IELs). So far, one of the nonclassical class I molecules(CD1d), is the best candidate for an antigen presenting molecule. |
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