van Praag M C, Mulder A A, Claas F H, Vermeer B J, Mommaas A M
Department of Dermatology, University Hospital Leiden, The Netherlands.
Clin Exp Immunol. 1994 Jan;95(1):73-7. doi: 10.1111/j.1365-2249.1994.tb06017.x.
The influence of low-dose, long-term ultraviolet B (UVB) light exposure on HLA class II-positive human epidermal Langerhans cells (LC) was studied using a sensitive immunoelectron microscopic technique for the ultrastructural assessment of HLA class II expression on LC and for quantification of these cells in situ. Six healthy Caucasian volunteers participated in the experiments and received thrice weekly UVB treatments for 4 weeks. The initial dose ranged from 30 to 50 mJ/cm2 and the total dose from 600 to 3500 mJ/cm2, depending on skin type. Suction blisters and biopsies were obtained before the start of the UVB protocol and 48 h after the last UVB irradiation, and processed for the mixed epidermal cell-lymphocyte reaction (MECLR) and electronmicroscopy, respectively. The MECLR was used as a measure of the immune response. The distribution of HLA class II molecules on LC was studied by incubating ultrathin cryosections of human skin tissue with an anti-HLA class II MoAb that was conjugated to 10 nm colloidal gold. Furthermore, the number of LC was assessed ultrastructurally, when they could be recognized by their unique cytoplasmic organelle, the Birbeck granule (BG). The UVB protocol that was employed caused a marked suppression of the MECLR responses. This UVB-induced reduction of the immune response was not paralleled by changes in HLA class II expression on LC, nor in the number of epidermal LC. These findings are further support for our hypothesis that UVB-induced immune suppression in the skin is not due to a depletion of local LC.
采用一种灵敏的免疫电子显微镜技术,研究低剂量、长期紫外线B(UVB)照射对人表皮中表达HLA-II类分子的朗格汉斯细胞(LC)的影响,该技术用于对LC上HLA-II类分子表达进行超微结构评估以及对这些细胞进行原位定量。6名健康的白种人志愿者参与了实验,每周接受3次UVB治疗,共4周。初始剂量根据皮肤类型在30至50 mJ/cm2之间,总剂量在600至3500 mJ/cm2之间。在UVB治疗方案开始前以及最后一次UVB照射后48小时获取抽吸水疱和活检组织,分别用于混合表皮细胞-淋巴细胞反应(MECLR)和电子显微镜检查。MECLR用作免疫反应的指标。通过将人皮肤组织的超薄冰冻切片与缀合有10 nm胶体金的抗HLA-II类单克隆抗体孵育,研究LC上HLA-II类分子的分布。此外,当LC可通过其独特的细胞质细胞器——伯贝克颗粒(BG)识别时,通过超微结构评估LC的数量。所采用的UVB治疗方案导致MECLR反应明显受到抑制。UVB诱导的这种免疫反应降低与LC上HLA-II类分子表达的变化以及表皮LC数量的变化均不平行。这些发现进一步支持了我们的假设,即皮肤中UVB诱导的免疫抑制并非由于局部LC的耗竭。