Koch Susanne, Kohl Kristine, Klein Elisabeth, von Bubnoff Dagmar, Bieber Thomas
Department of Dermatology, Friedrich-Wilhelms-University, Bonn, Germany.
J Allergy Clin Immunol. 2006 Jan;117(1):163-8. doi: 10.1016/j.jaci.2005.10.003. Epub 2005 Dec 2.
Langerhans cells (LCs) are epidermal antigen-presenting dendritic cells. They contain unique granules, known as Birbeck granules, which are substructures of the endosomal recycling compartment. LCs migrate from the epidermis to the regional lymph nodes for presentation of antigenic peptides to T cells. There LCs either initiate a primary immune response or induce antigen-specific tolerance. The replenishment of the LC pool in the epidermis is the topic of this review. Chemokines produced by epidermal keratinocytes and by dermal fibroblasts guide the arrest of LC precursors on endothelial cells of dermal venules, followed by their transmigration through endothelium and dermis toward the epidermis. One necessary prerequisite for this is the coordinated expression of adhesion receptors and counter-receptors on LC precursors and on endothelial and dermal cells. LC precursors attach to and degrade basement membrane proteins to penetrate the dermal matrix and the basement membrane of the dermal-epidermal junction. LC migration depends on the activity of matrix metalloproteinases, which are proteolytic endopeptidases cleaving matrix components. Matrix metalloproteinases also execute an important role in modulating inflammatory and immune responses by processing chemokines, which turns them into dual players for the immigration of LC precursors into the epidermis.
朗格汉斯细胞（LCs）是表皮抗原呈递树突状细胞。它们含有独特的颗粒，即伯贝克颗粒，是内体循环区室的亚结构。LCs从表皮迁移至局部淋巴结，将抗原肽呈递给T细胞。在那里，LCs要么引发初次免疫反应，要么诱导抗原特异性耐受。表皮中LC库的补充是本综述的主题。表皮角质形成细胞和真皮成纤维细胞产生的趋化因子引导LC前体细胞在内皮细胞上停滞，随后它们穿过内皮和真皮向表皮迁移。对此，一个必要的前提条件是LC前体细胞与内皮细胞和真皮细胞上的黏附受体和反受体的协调表达。LC前体细胞附着并降解基底膜蛋白，以穿透真皮基质和真皮 - 表皮连接处的基底膜。LC迁移取决于基质金属蛋白酶的活性，基质金属蛋白酶是切割基质成分的蛋白水解内肽酶。基质金属蛋白酶在通过加工趋化因子来调节炎症和免疫反应方面也发挥着重要作用，这使其成为LC前体细胞迁入表皮的双重作用因子。
