title: Effective blue light photodynamic therapy does not affect cutaneous langerhans cell number or oxidatively damage DNA.
abstract: BACKGROUND
  Photodynamic therapy (PDT) using aminolevulinic acid (ALA) with blue light or red light is effective for treating actinic keratoses (AKs). However, immunosuppression follows red light PDT, raising the spectre of skin cancer promotion in treated skin.
  
  
  OBJECTIVE
  To determine whether broad-area short incubation (BASI)-ALA-PDT using blue light immunosuppression immunosuppresses treated skin.
  
  
  METHODS
  Patients were evaluated clinically and by standardized facial biopsies of non-AK skin before, 24 hours and 1 month after customary blue light BASI-ALA-PDT. All biopsies were stained for markers of epidermal atypia and Langerhans cells (LCs); and at 24 hours to detect oxidative DNA damage.
  
  
  RESULTS
  Patients had an 81% reduction in AKs and slight improvement in clinical and histologic signs of photoaging after 1 month. The biopsied chronically photodamaged skin without clinically detectable AKs showed no effect of PDT on the LC number, distribution, or morphology; and no oxidative DNA damage, in contrast to the changes reported after customary red light PDT.
  
  
  CONCLUSIONS
  Customary blue light BASI-ALA-PDT does not affect the LC number or produce oxidative DNA damage, the sequelae of red light PDT responsible for immunosuppression in treated skin.
authors: *Department of Dermatology, Boston University School of Medicine, Boston, Massachusetts; †Trokhan Dermatology, Closter, New Jersey; ‡Division of Dermatology, Vanderbilt University School of Medicine, Nashville, Tennessee.
authors: Preethi
authors: P
authors: Ramaswamy
authors: Jennifer G
authors: JG
authors: Powers
authors: Jag
authors: J
authors: Bhawan
authors: Ildiko
authors: I
authors: Polyak
authors: Barbara A
authors: BA
authors: Gilchrest
mesh_terms: D000368:Aged; D000622:Aminolevulinic Acid / Q000494:pharmacology; D002452:Cell Count; D003116:Color; D004249:DNA Damage; D005260:Female; D006801:Humans; D007165:Immunosuppression Therapy; D015603:Keratinocytes / Q000737:chemistry; D055623:Keratosis, Actinic / Q000188:drug therapy* / Q000473:pathology; D019394:Ki-67 Antigen / Q000032:analysis; D007801:Langerhans Cells / Q000187:drug effects / Q000528:radiation effects*; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D010778:Photochemotherapy / Q000009:adverse effects / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology; D015595:Skin Aging / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects*; D016159:Tumor Suppressor Protein p53 / Q000032:analysis
chemical_list: D019394:Ki-67 Antigen; D017319:Photosensitizing Agents; D016159:Tumor Suppressor Protein p53; D000622:Aminolevulinic Acid