Dumay O, Karam A, Vian L, Moyal D, Hourseau C, Stoebner P, Peyron J L, Meynadier J, Cano J P, Meunier L
Laboratory of Drug Toxicology, University of Montpellier, Montpellier, France.
Br J Dermatol. 2001 Jun;144(6):1161-8. doi: 10.1046/j.1365-2133.2001.04225.x.
Ultraviolet (UV) B-induced effects on the skin immune system have been extensively investigated, but little is known regarding the immunological changes induced by UVA exposure of human skin. Recent data assessing the protection afforded by sunscreens against photoimmunosuppression stress the need for broad-spectrum sunscreens with an adequate UVA protection.
The purpose of this study was first to determine the changes observed in epidermal Langerhans cells (ELC) density and epidermal antigen-presenting cell (APC) activity after exposure of human skin to UVAI (340-400 nm) radiation, and secondly to assess the immune protection afforded in vivo by a sunscreen formulation containing a long wavelength UVA filter with a low UVA protection factor (UVA-PF = 3).
Epidermal cell (EC) suspensions were prepared from skin biopsies 3 days after exposure to a single dose of UVAI (either 30 or 60 J cm(-2)).
Flow-cytometric analysis of EC suspensions revealed that exposure to 60 J cm(-2) UVAI resulted in a decreased number of ELC without infiltration of CD36+ DR+ CD1a- antigen-presenting macrophages into the epidermis, and a significant reduction of HLA-DR expression on viable ELC. In vivo exposure to both 30 and 60 J cm(-2) resulted in a decreased allogeneic CD4+ T-cell proliferation induced by UVAI-irradiated ECs. The sunscreen application partially prevented (57 +/- 9%) the decrease in epidermal allogeneic APC activity induced by 60 J cm(-2) UVAI.
In vivo UVAI exposure of human skin results in a decreased number of ELC and in a downregulation of epidermal APC activity. This last effect is partially prevented by prior application of a sunscreen with a low UVAI-PF value. These results indicate that increasing the absorption of UV filters for long UVA wavelengths may lead to an improved immune protection.
紫外线B对皮肤免疫系统的影响已得到广泛研究，但关于UVA照射人体皮肤引起的免疫变化却知之甚少。近期评估防晒霜对光免疫抑制保护作用的数据强调了需要具有足够UVA防护能力的广谱防晒霜。
本研究的目的首先是确定人体皮肤暴露于UVA1（340 - 400nm）辐射后表皮朗格汉斯细胞（ELC）密度和表皮抗原呈递细胞（APC）活性的变化，其次是评估含有低UVA防护因子（UVA-PF = 3）的长波长UVA滤光剂的防晒配方在体内提供的免疫保护。
在单次暴露于UVA1（30或60J/cm²）3天后，从皮肤活检组织制备表皮细胞（EC）悬液。
对EC悬液的流式细胞术分析显示，暴露于60J/cm²的UVA1会导致ELC数量减少，且无CD36⁺DR⁺CD1a⁻抗原呈递巨噬细胞浸润到表皮中，同时活的ELC上HLA-DR表达显著降低。体内暴露于30和60J/cm²均会导致UVA1照射的EC诱导的同种异体CD4⁺T细胞增殖减少。涂抹防晒霜部分预防了（57±9%）60J/cm²UVA1诱导的表皮同种异体APC活性降低。
人体皮肤在体内暴露于UVA1会导致ELC数量减少以及表皮APC活性下调。预先涂抹低UVA1-PF值的防晒霜可部分预防后一种效应。这些结果表明，增加对长UVA波长紫外线滤光剂的吸收可能会带来更好的免疫保护。
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