Girolomoni G, Zambruno G, Manfredini R, Zacchi V, Ferrari S, Cossarizza A, Giannetti A
Department of Dermatology, University of Modena, Italy.
J Invest Dermatol. 1994 Jul;103(1):54-9. doi: 10.1111/1523-1747.ep12389619.
Langerhans cells (LC) belong to the dendritic cell lineage and are the principal antigen-presenting cells of squamous epithelia. Short-term cultured LC (cLC) exhibit a marked augmented capacity to stimulate allogeneic T cells and acquire the ability to activate naive T cells, probably in relation to enhanced expression of accessory signals. In this study, we evaluated the expression of B7 costimulatory molecule (CD80) in human freshly isolated (fLC) and cLC at both the protein and mRNA level. Staining of frozen skin sections did not reveal any epidermal dendritic cell reactive with either of two different anti-B7 monoclonal antibodies. fLC in suspension did not exhibit any B7 staining as evaluated by two-color flow-cytometry analysis and immunoelectron microscopy. In contrast, LC that were cultured for 24-72 h displayed strong surface B7 reactivity with a characteristic patchy pattern. Treatment with dispase and trypsin did not reduce B7 staining of cLC. Following warming to 37 degrees C, cLC tagged with anti-B7 monoclonal antibody and gold-conjugated secondary antibody could internalize surface B7 by using the organelles of receptor-mediated endocytosis. B7 mRNA, detected by the reverse-transcriptase polymerase chain reaction technique, was expressed at a low level in purified (> 90% HLA-DR+) fLC but not in LC-depleted epidermal cells, and was markedly upregulated in purified cLC. The results indicate that 1) fLC do not express B7 protein on their surface, but acquire B7 during culture, 2) surface B7 is not sensitive to trypsin, 3) B7 expression is regulated primarily at the mRNA level, and 4) membrane B7 can be internalized within cLC. B7 molecule on CLC may be relevant to their increased antigen-presenting cell potency and ability to stimulate naive T lymphocytes.
朗格汉斯细胞（LC）属于树突状细胞谱系，是鳞状上皮的主要抗原呈递细胞。短期培养的LC（cLC）表现出显著增强的刺激同种异体T细胞的能力，并获得激活初始T细胞的能力，这可能与辅助信号表达增强有关。在本研究中，我们在蛋白质和mRNA水平评估了人新鲜分离的（fLC）和cLC中B7共刺激分子（CD80）的表达。冷冻皮肤切片染色未发现与两种不同抗B7单克隆抗体中的任何一种发生反应的表皮树突状细胞。通过双色流式细胞术分析和免疫电子显微镜评估，悬浮液中的fLC未表现出任何B7染色。相反，培养24 - 72小时的LC表现出强烈的表面B7反应性，呈特征性的斑片状模式。用Dispase和胰蛋白酶处理并未降低cLC的B7染色。升温至37摄氏度后，用抗B7单克隆抗体和金标记二抗标记的cLC可通过受体介导的内吞细胞器内化表面B7。通过逆转录聚合酶链反应技术检测到的B7 mRNA在纯化的（>90% HLA - DR +）fLC中低水平表达，但在LC缺失的表皮细胞中不表达，并且在纯化的cLC中显著上调。结果表明：1）fLC表面不表达B7蛋白，但在培养过程中获得B7；2）表面B7对胰蛋白酶不敏感；3）B7表达主要在mRNA水平受到调控；4）膜B7可在cLC内内化。CLC上的B7分子可能与其增强的抗原呈递细胞效能和刺激初始T淋巴细胞的能力有关。
