Indications and action mechanisms of phototherapy.
Recently phototherapy has become one of the most commonly used modalities for the treatment of a variety of skin diseases, although the action mechanisms have not been fully understood. The inhibitory effect of UVR on DNA synthesis may be one of the actions for proliferating skin diseases. However, phototherapy is also used for the treatment of allergic or autoimmune diseases. It has been confirmed that the skin is an important immunologic organ whose constitutive cells are all involved in immunologic reactions. We have investigated the effects of PUVA and UVB radiation on the immunocompetent cells, including Langerhans cells, T lymphocytes, mast cells, endothelial cells and natural killer cells. Exposure to UVR inhibits contact sensitization to haptens applied not only to the irradiated skin area but also to the non-irradiated distant skin when the exposure dose is relatively high and/or the application skin area is large. In addition, hapten-specific tolerance develops by the generation of suppressor T cells. Phototherapy is also useful for immediate type hypersensitivity such as urticaria. Action mode in the case may be the inhibitory effects of UVR on histamine release from mast cells. The results obtained from these experiments suggest that phototherapy exerts its anti-allergic and anti-inflammatory effects through immunosuppression.
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Department of Dermatology, Kansai Medical University, Fumizono 10-15, Moriguchi, Osaka, Japan.
D000276:Adjuvants, Immunologic / Q000096:biosynthesis; D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000528:radiation effects; D004247:DNA / Q000096:biosynthesis; D004730:Endothelium, Vascular / Q000276:immunology / Q000528:radiation effects; D006801:Humans; D007165:Immunosuppression Therapy; D007694:Killer Cells, Natural / Q000276:immunology / Q000528:radiation effects; D008214:Lymphocytes / Q000276:immunology / Q000528:radiation effects; D008407:Mast Cells / Q000276:immunology / Q000528:radiation effects; D011701:PUVA Therapy; D010789:Phototherapy; D012871:Skin Diseases / Q000188:drug therapy / Q000276:immunology / Q000628:therapy*; D014466:Ultraviolet Rays
D000276:Adjuvants, Immunologic; D004247:DNA