Evidence that Singlet Oxygen-induced Human T Helper Cell Apoptosis Is the Basic Mechanism of Ultraviolet-A Radiation Phototherapy |
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| Authors: | Akimichi Morita Thomas Werfel Helger Stege Constanze Ahrens Karin Karmann Markus Grewe Susanne Grether-Beck Thomas Ruzicka Alexander Kapp Lars-Oliver Klotz Helmut Sies Jean Krutmann |
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| Affiliation: | From *Clinical and Experimental Photodermatology, Department of Dermatology, Heinrich-Heine-University of Düsseldorf, D-40225 Düsseldorf; ‡Department of Dermatology, Hannover Medical School, D-30625 Hannover; and §Institute of Physiological Chemistry I, Heinrich-Heine-University, D-40225 Düsseldorf, Germany |
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| Abstract: | Ultraviolet A (UVA) irradiation is effectively used to treat patients with atopic dermatitis and other T cell mediated, inflammatory skin diseases. In the present study, successful phototherapy of atopic dermatitis was found to result from UVA radiation-induced apoptosis in skin-infiltrating T helper cells, leading to T cell depletion from eczematous skin. In vitro, UVA radiation-induced human T helper cell apoptosis was mediated through the FAS/FAS-ligand system, which was activated in irradiated T cells as a consequence of singlet oxygen generation. These studies demonstrate that singlet oxygen is a potent trigger for the induction of human T cell apoptosis. They also identify singlet oxygen generation as a fundamental mechanism of action operative in phototherapy. |
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