Salmon J K, Armstrong C A, Ansel J C
Department of Dermatology, Oregon Health Science University School of Medicine, Portland 97201.
West J Med. 1994 Feb;160(2):146-52.
As a protective interface between internal organs and the environment, the skin encounters a host of toxins, pathogenic organisms, and physical stresses. To combat these attacks on the cutaneous microenvironment, the skin functions as more than a physical barrier: it is an active immune organ. Immune responses in the skin involve an armamentarium of immune-competent cells and soluble biologic response modifiers including cytokines. Traversed by a network of lymphatic and blood vessels, the dermis contains most of the lymphocytes in the skin, other migrant leukocytes, mast cells, and tissue macrophages. Although the epidermis has no direct access to the blood or lymphatic circulation, it is equipped with immune-competent cells: Langerhans cells, the macrophage-like antigen-presenting cells of the epidermis; keratinocytes, epithelial cells with immune properties; dendritic epidermal T lymphocytes, resident cells that may serve as a primitive T-cell immune surveillance system; epidermotropic lymphocytes, migrants from vessels in the dermis; and melanocytes, epidermal pigment cells with immune properties. Although the components of the epidermis and dermis work in concert to execute immune responses in the skin, for purposes of this review, we focus on the cells and cytokines of the epidermal immunologic unit, the frontline of immune protection against environmental toxins and microbes.
作为内部器官与外界环境之间的保护性界面，皮肤会接触到大量毒素、致病生物和物理压力。为抵御这些对皮肤微环境的侵袭，皮肤的功能远不止是一个物理屏障：它是一个活跃的免疫器官。皮肤中的免疫反应涉及一系列免疫活性细胞和可溶性生物反应调节剂，包括细胞因子。真皮层中有淋巴管和血管网络穿过，包含了皮肤中大部分淋巴细胞、其他游走白细胞、肥大细胞和组织巨噬细胞。尽管表皮无法直接进入血液循环或淋巴循环，但它配备了免疫活性细胞：朗格汉斯细胞，即表皮中类似巨噬细胞的抗原呈递细胞；角质形成细胞，具有免疫特性的上皮细胞；树突状表皮T淋巴细胞，可能作为原始T细胞免疫监视系统的驻留细胞；亲表皮淋巴细胞，从真皮层血管迁移而来的细胞；以及黑素细胞，具有免疫特性的表皮色素细胞。尽管表皮和真皮的组成部分协同工作以执行皮肤中的免疫反应，但在本综述中，我们将重点关注表皮免疫单位的细胞和细胞因子，它们是抵御环境毒素和微生物的免疫保护前线。
