title: Accumulation of apoptotic cells in the epidermis of patients with cutaneous lupus erythematosus after ultraviolet irradiation.
abstract: OBJECTIVE
  To examine whether apoptosis contributes to the pathogenesis of skin lesions in patients with cutaneous lupus erythematosus (CLE) after ultraviolet (UV) irradiation.
  
  
  METHODS
  In situ nick translation and TUNEL were performed to detect apoptosis in 85 skin biopsy specimens from patients with various subtypes of CLE. Specimens from normal healthy donors and patients with polymorphous light eruption were used as controls. In addition to assessment of primary lesions, provocative phototesting was carried out to investigate events occurring secondary to UV irradiation during a very early stage of lesion formation.
  
  
  RESULTS
  A significant increase in apoptotic nuclei was found in the upper epidermal layer of primary and UV light-induced skin lesions of CLE patients compared with controls. In tissue sections obtained from control subjects at 24 hours after a single exposure to UV light, a slight increase in the count of epidermal apoptotic nuclei was present as compared with skin tissue from CLE patients obtained under the same conditions before lesion formation. In sections obtained from controls at 72 hours after irradiation, a significant decrease in the apoptotic nuclei count was observed, consistent with a proper clearance of apoptotic cells in the period between 24 and 72 hours after irradiation. In striking contrast, the number of apoptotic nuclei increased significantly within this period in tissue sections from patients with CLE.
  
  
  CONCLUSIONS
  These data support the hypothesis that apoptotic cells accumulate in the skin of patients with CLE after UV irradiation, as a result of impaired or delayed clearance. The nonengulfed cells may undergo secondary necrosis and release proinflammatory compounds and potential autoantigens, which may contribute to the inflammatory micromilieu that leads to formation of skin lesions in this disease.
authors.affiliation: University of Düsseldorf, Dusseldorf, Germany. kuhnan@uniduesseldorf.de
authors.forename: Annegret
authors.initials: A
authors.lastname: Kuhn
authors.forename: Martin
authors.initials: M
authors.lastname: Herrmann
authors.forename: Susanne
authors.initials: S
authors.lastname: Kleber
authors.forename: Maria
authors.initials: M
authors.lastname: Beckmann-Welle
authors.forename: Karin
authors.initials: K
authors.lastname: Fehsel
authors.forename: Ana
authors.initials: A
authors.lastname: Martin-Villalba
authors.forename: Percy
authors.initials: P
authors.lastname: Lehmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Ruzicka
authors.forename: Peter H
authors.initials: PH
authors.lastname: Krammer
authors.forename: Victoria
authors.initials: V
authors.lastname: Kolb-Bachofen
mesh_terms: D000328:Adult; D000368:Aged; D017209:Apoptosis; D004817:Epidermis / Q000473:pathology*; D005260:Female; D006801:Humans; D020287:In Situ Nick-End Labeling; D008178:Lupus Erythematosus, Cutaneous / Q000473:pathology* / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D014467:Ultraviolet Therapy