COMPARATIVE POTENCY OF BROAD-BAND AND NARROW-BAND PHOTOTHERAPY SOURCES TO INDUCE EDEMA, SUNBURN CELLS AND UROCANIC ACID PHOTOISOMERIZATION IN HAIRLESS MOUSE SKIN |
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| Authors: | Neil K Gibbs Mary Norval Nicola J Traynor John C Crosby Graham Lowe Brian E Johnson |
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| Institution: | Photobiology Unit, Ninewells Hospital, University of Dundee, DD1 9SY;Department of Medical Microbiology, University of Edinburgh;School of Chemistry, University of Bristol, UK |
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| Abstract: | The Philips TL01 narrow-band (311–313 nm) fluorescent lamp provides effective phototherapy for psoriasis and atopic eczema while emitting less erythemogenic radiation than conventional broad-band ( e.g . Philips TL12; 270–350 nm) sources. We studied the potency of TL01 and TL12 radiation to induce edema and sunburn cells (SBC) and to photoisomerize naturally occumng trans- urocanic acid (UCA) to cis -UCA in hairless mouse skin. Cis -UCA has immunosuppressive properties and is a putative mediator of UV-induced suppression of immune responses. For each source, there was UV dose dependence for all three responses. Within the dose ranges used, the potency ratio of TL12: TL01 radiation to induce equivalent edema and SBC was about 6:1. However, the potency ratio to induce cis-IJCA was less than 2.3:1. Therefore, at a given level of edema or SBC induction, TL01 was more efficient than TL12 at UCA photoisomerization. The TL01 induction of immunomodulating cis -UCA, while causing minimal skin injury, may relate to the therapeutic efficacy of this source in skin conditions with an immunological component. |
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