Maric I, Holt P G, Perdue M H, Bienenstock J
Department of Pathology, McMaster University, Hamilton, Ontario, Canada.
J Immunol. 1996 Feb 15;156(4):1408-14.
Many tissues are found to contain populations of cells with an unusual dendritic shape, high levels of surface expression of MHC class II (Ia) gene products, and strong accessory function for the stimulation of specific clones of quiescent T lymphocytes. Dendritic cells (DC) represent major population of "professional" APC in various lymphoid and nonlymphoid tissues, distinct from cells of the monocyte/macrophage lineage. Among the best characterized nonlymphoid dendritic cells are epidermal Langerhans cells, but it has been shown that interstitium and epithelium of other organs also contain irregularly shaped, strongly MHC class II positive cells. In recent years, DC have been localized to alveolar septa in the lung, as well as within and just beneath airway epithelium, comprising a tightly meshed network that is reminiscent of epidermal Langerhans cells. In the gastrointestinal tract, conventional immunohistochemical analysis of mucosal class II MHC (Ia) staining reveals a morphologically heterogeneous pattern of staining in the lamina propria. DC that exhibit strong Ag-presenting activity in vitro have been extracted from enzymatic digests of colonic mucosa, but no previous reports of MHC class II-positive cells with pleiomorphic morphology have been recorded within the epithelium of the intestine. Employing a novel combination of nonconventional section planes, pre-embedding fixation, and immunohistochemical techniques, we now demonstrate Ia staining of cells with classical DC morphology within the epithelium of the intestine in normal specific pathogen-free rats. Our investigation suggests that cells with the morphologic and phenotypical characteristics of DC are present within the mucosal epithelium of the rat jejunum and colon, comprising a significant organized network. The number of DC within epithelium of the colon was 117 +/- 20 per 10-microns-thick cross-section. These findings have important theoretical implications for research on Ag processing and T cell activation in the context of allergic and infectious diseases in the gastrointestinal tract.
许多组织中都发现含有一群细胞，这些细胞具有异常的树突状形态、高水平的主要组织相容性复合体II类（Ia）基因产物的表面表达，以及刺激静止T淋巴细胞特异性克隆的强大辅助功能。树突状细胞（DC）是各种淋巴组织和非淋巴组织中“专业”抗原呈递细胞（APC）的主要群体，与单核细胞/巨噬细胞谱系的细胞不同。在特征最明确的非淋巴树突状细胞中，有表皮朗格汉斯细胞，但已表明其他器官的间质和上皮中也含有形状不规则、MHC II类强阳性的细胞。近年来，DC已定位到肺的肺泡隔以及气道上皮内和上皮下方，形成一个紧密交织的网络，让人联想到表皮朗格汉斯细胞。在胃肠道中，对黏膜II类MHC（Ia）染色的传统免疫组织化学分析显示固有层中染色的形态学异质性模式。已从结肠黏膜的酶消化物中提取出在体外具有强大抗原呈递活性的DC，但此前在肠道上皮内尚未有关于具有多形形态的MHC II类阳性细胞的报道。采用非常规切片平面、包埋前固定和免疫组织化学技术的新组合，我们现在证明在正常无特定病原体大鼠的肠道上皮内，具有经典DC形态的细胞有Ia染色。我们的研究表明，具有DC形态学和表型特征的细胞存在于大鼠空肠和结肠的黏膜上皮内，形成一个重要的有组织网络。结肠上皮内DC的数量为每10微米厚的横截面117±20个。这些发现对胃肠道过敏性和感染性疾病背景下的抗原加工和T细胞活化研究具有重要的理论意义。
