The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia.
Semin Cell Dev Biol. 2015 May;41:23-9. doi: 10.1016/j.semcdb.2014.02.001. Epub 2014 Feb 7.
Langerhans cells (LCs) are the unique antigen-presenting cell of the epidermis. LCs have long been depicted in textbooks as the archetypical dendritic cell that alerts the immune system upon pathogen induced skin barrier breakage, however recent findings argue instead for a more tolerogenic function. While the LCs that populate the epidermis in steady-state arise from progenitors that seed the skin during embryogenesis, it is now apparent that a second pathway generating LCs from a bone marrow derived progenitor is active in inflammatory settings. This review emphasizes the determinants underpinning the establishment of the LC network in steady-state and under inflammatory conditions, as well as the transcriptional machinery governing their differentiation. The dual origin of LCs raises important questions about the functional differences between these subsets in balancing the epidermal immune response between immunity and tolerance.
郎格汉斯细胞（LCs）是表皮中独特的抗原呈递细胞。LCs 在教科书中一直被描绘为典型的树突状细胞，在病原体诱导的皮肤屏障破坏时会激活免疫系统，但最近的研究结果却表明其具有更耐受的功能。虽然在稳态时，表皮中的 LCs 来源于胚胎发生期间在皮肤中播种的祖细胞，但现在显然，在炎症环境中，有一种从骨髓衍生祖细胞产生 LCs 的第二途径是活跃的。这篇综述强调了在稳态和炎症条件下建立 LC 网络的决定因素，以及调节其分化的转录机制。LC 的双重起源提出了关于这些亚群在平衡免疫和耐受之间的表皮免疫反应方面的功能差异的重要问题。
