Premium
Repeated low‐dose ultraviolet (UV) B exposures of humans induce limited photoprotection against the immune effects of erythemal UVB radiation
Author(s) -
Narbutt J.,
Lesiak A.,
SysaJedrzejowska A.,
Wozniacka A.,
CierniewskaCieslak A.,
Boncela J.,
Jochymski C.,
Kozlowski W.,
Zalewska A.,
Skibinska M.,
Norval M.
Publication year - 2007
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/j.1365-2133.2006.07670.x
Subject(s) - photoprotection , pyrimidine dimer , cytokine , immune system , medicine , erythema , immunology , chemistry , biochemistry , dna repair , photosynthesis , gene
Summary Background Exposure of human subjects to ultraviolet (UV) B radiation causes immunosuppression. Most experiments to date have not tested the effects of low daily doses of UVB radiation. Objectives To ascertain whether photoprotection against several UV‐induced immune effects might develop following repeated exposure. Methods Groups of approximately 30 healthy individuals were given whole‐body UVB irradiation on each of 10 consecutive days with 0.7 minimal erythema dose, or whole‐body irradiation as before followed by a single erythemal UVB dose on a small body area, or irradiated only with a single erythemal UVB dose on a small body area, or were not irradiated. They were sensitized with diphenylcyclopropenone (DPCP) 24 h after the final dose, and skin biopsies collected to assess cytokine mRNA expression and the number of cells with thymine dimers and expression cyclooxygenase (COX)‐1 and COX‐2. Results The contact hypersensitivity (CHS) response to DPCP was significantly lower in the three irradiated groups compared with the unirradiated controls, while cutaneous interleukin (IL)‐1 β , IL‐6, IL‐10 and tumour necrosis factor‐ α mRNAs, COX‐1 and COX‐2 and thymine dimers were all significantly higher. When the single erythemal UVB dose was given following the repeated low exposures, a slight downregulation in cytokine expression and thymine dimer formation was indicated. Conclusions The repeated low doses of UVB protected to a limited extent against the effects of an erythemal UVB dose on cytokine expression and thymine dimer formation, but not on CHS or COX enzymes.