title: The combination of the Zenon labeling technique and microscopic image analysis to study cell populations in normal and psoriatic epidermis.
abstract: BACKGROUND
  In order to better characterize epidermal cell populations in psoriatic vs. normal skin, fluorescent immunohistochemical techniques were extended with a new labeling technique. The Zenon technique conjugates primary antibodies rapidly and quantitatively after which they are used in the same manner as covalently labeled primary antibodies. Digital microscopic images of epidermal expression of keratin 10 and keratin 6 (differentiation), Ki-67 antigen (proliferation), and keratin 15 and beta-1 integrin (basal layer) were analyzed in a standardized way. Co-expression of different proteins was demonstrated.
  
  
  METHODS
  Sections of normal skin and psoriatic lesions were compared immunohistochemically. Antibodies against keratin 6, 10, and 15 were labeled with the Zenon technique. Antibodies against the Ki-67 antigen and beta-1 integrin were covalently fluorescein isothiocyanate-labeled. Using standardized image analysis, intensity and positive surface area of the different antibodies in the epidermis were measured.
  
  
  RESULTS
  The number of Ki-67-antigen positive cells was significantly increased in lesional psoriatic skin. Intensity and positive surface area of keratin 10 and beta-1 integrin were significantly decreased in comparison to normal epidermis. Differential expression of keratin 6 and keratin 15 was demonstrated.
  
  
  CONCLUSIONS
  Using Zenon technology and image analysis, a description of morphology, co-expression, and quantification of representative markers for epidermal cell populations is possible.
authors.affiliation: Department of Dermatology, University Medical Centre Nijmegen, 6500 HB Nijmegen, The Netherlands.
authors.forename: Mirella W F M
authors.initials: MW
authors.lastname: van Duijnhoven
authors.forename: Peter C M
authors.initials: PC
authors.lastname: van de Kerkhof
authors.forename: Marcel C
authors.initials: MC
authors.lastname: Pasch
authors.forename: Leon
authors.initials: L
authors.lastname: Muys
authors.forename: Piet E J
authors.initials: PE
authors.lastname: van Erp
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D002452:Cell Count; D004817:Epidermis / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019012:Integrin beta1 / Q000378:metabolism; D007633:Keratins / Q000378:metabolism; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000378:metabolism*; D013194:Staining and Labeling / Q000379:methods*
chemical_list: D015415:Biomarkers; D005456:Fluorescent Dyes; D019012:Integrin beta1; D019394:Ki-67 Antigen; D007633:Keratins