THE PHOTOBIOLOGICAL ANALYSIS AND THE CLINICAL APPLICATION OF UVA1

紫外线A-1 （340- 400nm）辐射可高效诱导皮肤浸润性t细胞凋亡，从而对t细胞介导的皮肤疾病，如特应性皮炎和皮肤t细胞淋巴瘤（UVA-1光疗）患者发挥有益作用。在体外研究中，我们报告了恶性和正常t细胞对UVA-1辐射诱导的凋亡的易感性不同。剂量反应研究显示，来自成人T细胞白血病患者或Sezary综合征患者的恶性CD4+ T细胞以及来自不同恶性T细胞系（HUT 102、ATL102、HPB-ALL、Jurkat、MOLT4）的细胞在暴露后4小时（早期凋亡）和24小时（晚期凋亡）时对UVA-1辐射诱导的凋亡的易感性明显高于正常的非恶性CD4+ T细胞（5个不同供体，p<0.05）。这种差异是UVA-1辐射所特有的，因为当UVA-1辐射或外源性添加的细胞渗透性神经酰胺刺激诱导细胞凋亡时，没有检测到这种差异。先前的研究表明，UVA-1辐射诱导的t细胞凋亡是通过单线态氧的产生启动的，随后通过FAS/FASL系统介导。这与目前的观察结果一致，即用单线态产氧系统刺激未辐照细胞诱导恶性细胞的凋亡程度大于非恶性正常细胞，这种差异与UVA-1辐照后观察到的差异相似。此外，通过FAS抗体或FASL转染物的重复刺激下调恶性T细胞（Jurkat）中FAS表面表达与抑制UVA-1辐射/单线态氧诱导的这些细胞凋亡有关。众所周知，fas诱导的细胞凋亡是由半胱天冬酶进一步下游介导的。因此，我们非常感兴趣的是，caspase抑制剂Z-VADfmk的加入降低了干扰素-γ刺激（已知可上调caspase水平，包括caspase-3），增加了t细胞对UVA-1辐射诱导的凋亡的敏感性。此外，恶性t细胞的procaspase 3水平明显高于正常细胞。这些研究表明，人类t细胞对UVA-1辐射诱导的凋亡的易感性与caspase 3等caspase的可用性有关，而针对上调caspase水平的策略可能会提高UVA-1光疗的疗效。少

Ultraviolet A-1 (340-400 nm) radiation is highly effective in inducing apoptosis in skin-infiltrating T-cells and thereby exerts beneficial effects in patients with T-cell-mediated skin diseases such as atopic dermatitis and cutaneous T-cell lymphoma (UVA-1 phototherapy). In the in-vitro study we report that malignant and normal T-cells differ in their susceptibility towards UVA-1 radiation-induced apoptosis. Dose-response studies revealed that malignant CD4+ T-cells isolated from a patient with adult T cell leukemia or from a patient with Sezary's syndrome as well as cells from different, malignant T cell lines (HUT 102,ATL102,HPB-ALL, Jurkat, MOLT4) exhibited a significantly higher susceptibility towards UVA-1 radiation-induced apoptosis 4 hours (early apoptosis) and 24 hours (late apoptosis) after exposure than normal, nonmalignant CD4+ T-cells (5 different donors ; p<0.05). This difference was specific for UVA-1 irradiation because it was not detected when apoptosis was induced in … More these cells through exposure to UVB radiation or stimulation with exogenously added, cell permeable ceramides. In previous studies it has been shown that UVA-1 radiation-induced T-cell apoptosis is initiated through the generation of singlet oxygen and subsequently mediated through the FAS/FASL system. This is in agreement with the present observation that stimulation of unirradiated cells with a singlet oxygen generating system induced apoptosis in malignant cells to a greater extent than in nonmalignant, normal cells, and this difference was similar to that observed after UVA-1 irradiation. Moreover, downregulation of FAS surface expression in malignant T cells (Jurkat) through repetitive stimulation with FAS antibody or FASL transfectant was associated with the inhibition of UVA-1 radiation/singlet oxygen-induced apoptosis in these cells. It is well known that FAS-induced apoptosis is mediated further downstream by caspases. It was thus of great interest to learn that addition of the caspase inhibitor Z-VADfmk decreased and interferon-γ stimulation, which is known to upregulate caspase levels including caspase-3,increased the sensitivity of T-cells towards UVA-1 radiation-induced apoptosis. Moreover, malignant T-cells had significantly higher procaspase 3 levels when compared with normal cells. These studies indicate that the susceptibility of human T-cells towards UVA-1 radiation-induced apoptosis is related to the availability of caspases such as caspase 3 and that strategies directed at upregulating caspase levels may increase the efficacy of UVA-1 phototherapy. Less