Rambukkana A, Bos J D, Irik D, Menko W J, Kapsenberg M L, Das P K
Department of Dermatology, University of Amsterdam, The Netherlands.
Lab Invest. 1995 Oct;73(4):521-31.
Epidermal Langerhans cells (ELC) play a critical role in the initiation of cutaneous immune responses. ELC are characterized by the expression of major histocompatibility complex (MHC) class II Ag and a number of adhesion/costimulatory molecules. Evidence suggests that cytokines induced within the epidermis regulate the functions of ELC, including their phenotypic expression. In the human system, no information is available regarding the behavior of the ELC in situ: their changes in morphology, expression of functional molecules or migration within the microenvironment. In the present study, using an ex vivo human skin organ culture model, we addressed the above questions and also examined the phenotypic modulation of ELC in situ by cytokines.
Skin explants were cultured either in a Trowell-type method or free in the medium. Skin explants were cultured with and without cytokines and were processed for light and electron microscopy and for immunohistochemical definition of ELC phenotypes.
In the Trowell-type skin organ culture, morphologic integrity of ELC, CD1a molecule, and Birbeck granules could be preserved intact up to 3 to 4 days in culture. During the first 3 days of culture, the intensity of MHC-II (HLA-DR, DP, and DQ) and CD1a expression on ELC increased sharply, and the dendritic appearance of ELC became more prominent at Day 3. Adhesion molecules, ICAM-1, LFA-3, HECA-452, sLx, and B7/BB1 were also spontaneously acquired in varying amounts by CD1a+ ELC after 3 days in culture. Significant increase of CD1a and ICAM-1 expression on ELC was observed within 12 hours, when skin explants were cultured free in the medium with GM-CSF and TNF-alpha, respectively. Further, we demonstrated spontaneous migration of ELC within the epidermis and then to the dermis during the Trowell-type skin culture. We also showed the migration of ELC out of the human skin when skin explants were cultured directly in the medium.
Human ELC showed significant phenotypic changes within the epidermis and acquired migratory capacity during the skin organ culture. ELC in skin organ culture appear to undergo a phenotypic maturation within the epidermis. ELC in situ rapidly respond to GM-CSF and TNF-alpha by increasing the expression of CD1a and ICAM-1 molecules, respectively. These results suggest the modulation of phenotypic characteristics of ELC and their migration in response to the changes of epidermal microenvironment and cytokines and implicate the potential use of skin organ culture model to elucidate the role of human ELC in the immunopathology of skin diseases.
表皮朗格汉斯细胞（ELC）在皮肤免疫反应的启动中起关键作用。ELC的特征是表达主要组织相容性复合体（MHC）II类抗原和多种黏附/共刺激分子。有证据表明，表皮内诱导产生的细胞因子可调节ELC的功能，包括其表型表达。在人类系统中，关于ELC在原位的行为尚无信息：它们在形态、功能分子表达或微环境内迁移方面的变化。在本研究中，我们使用体外人皮肤器官培养模型解决了上述问题，并研究了细胞因子对原位ELC表型的调节作用。
皮肤外植体采用Trowell型方法或在培养基中游离培养。皮肤外植体在有或无细胞因子的情况下培养，并进行光镜和电镜检查以及ELC表型的免疫组化鉴定。
在Trowell型皮肤器官培养中，ELC的形态完整性、CD1a分子和伯贝克颗粒在培养3至4天内可保持完整。在培养的前3天，ELC上MHC-II（HLA-DR、DP和DQ）和CD1a的表达强度急剧增加，ELC的树突状外观在第3天变得更加明显。培养3天后，CD1a+ ELC还会自发地不同程度获得黏附分子ICAM-1、LFA-3、HECA-452、sLx和B7/BB1。当皮肤外植体分别在含有GM-CSF和TNF-α的培养基中游离培养时，在12小时内观察到ELC上CD1a和ICAM-1表达显著增加。此外，我们证明了在Trowell型皮肤培养过程中ELC在表皮内自发迁移，然后迁移至真皮。我们还展示了将皮肤外植体直接在培养基中培养时ELC从人皮肤中迁出的情况。
人ELC在表皮内表现出显著的表型变化，并在皮肤器官培养过程中获得迁移能力。皮肤器官培养中的ELC似乎在表皮内经历表型成熟。原位ELC分别通过增加CD1a和ICAM-1分子的表达对GM-CSF和TNF-α迅速作出反应。这些结果表明ELC的表型特征及其迁移受表皮微环境和细胞因子变化的调节，并暗示皮肤器官培养模型在阐明人ELC在皮肤疾病免疫病理学中的作用方面具有潜在用途。
