title: Double trouble from sunburn: UVB-induced erythema is associated with a transient decrease in skin pigmentation.
abstract: BACKGROUND
  Ultraviolet B (UVB) radiation may cause an immediate inflammatory response followed by a delayed increase in skin pigmentation. The early time course of erythema and pigmentation has so far not been monitored simultaneously by photometric measurements.
  
  
  METHODS
  Test areas on the volar forearms of 15 volunteers were irradiated with 210 mJ/cm(2) UVB. Skin erythema and pigmentation were determined photometrically at time 0, after 6 h, and after 1, 2, 3 and 7 days. Punch biopsies were taken before irradiation, after 6 h and after 7 days. Melanocytes were stained using the DOPA method.
  
  
  RESULTS
  UVB irradiation caused an increase in skin erythema at all time points, peaking at 24 h and slowly decreasing until day 7. Surprisingly, this was associated with a pronounced decrease in skin pigmentation at early readings. DOPA staining of melanocytes confirmed this observation. Only after 7 days was there an increase in skin pigmentation over the initial levels.
  
  
  CONCLUSIONS
  Acute UVB-induced skin erythema seems to be associated with increased susceptibility to the deleterious effects of solar radiation due to a concomitant decrease in skin pigmentation. These findings underline the importance of avoiding even moderate sunburns and of slowly adapting the skin to solar radiation.
authors.affiliation: Department of Dermatology, Competence Center skintegral, University Medical Center Freiburg, Freiburg, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Casetti
authors.forename: A
authors.initials: A
authors.lastname: Miese
authors.forename: M L
authors.initials: ML
authors.lastname: Mueller
authors.forename: J C
authors.initials: JC
authors.lastname: Simon
authors.forename: C M
authors.initials: CM
authors.lastname: Schempp
mesh_terms: D000328:Adult; D001706:Biopsy; D004295:Dihydroxyphenylalanine; D004890:Erythema / Q000209:etiology* / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008544:Melanocytes / Q000528:radiation effects; D010783:Photometry; D012880:Skin Pigmentation / Q000528:radiation effects*; D013194:Staining and Labeling; D013471:Sunburn / Q000473:pathology*; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D004295:Dihydroxyphenylalanine