title: Memory effector (CD45RO+) and cytotoxic (CD8+) T cells appear early in the margin zone of spreading psoriatic lesions in contrast to cells expressing natural killer receptors, which appear late.
abstract: BACKGROUND
  An influx of immunocytes, increased epidermal proliferation and abnormal keratinization are hallmarks of the psoriatic lesion. T-lymphocyte subsets in particular activated effector memory T cells and natural killer (NK) T cells have been suggested to play an important role in the pathogenesis of psoriasis.
  
  
  OBJECTIVE
  In the present study we investigated the number of T-cell subsets (CD4, CD8, CD45RO, CD45RA, CD2, CD25), cells expressing NK receptors (CD94 and CD161), the proliferation marker Ki67 and the keratinization marker keratin (K10) across the margin of the spreading psoriatic plaque: distant uninvolved skin, the outer margin (immediately outside the clinical edge), the inner margin (immediately inside the clinical edge) and the central area.
  
  
  METHODS
  Eight patients with active psoriasis vulgaris participated in this study. Biopsies were taken from the spreading psoriatic lesion from the distant uninvolved skin, the outer margin, the inner margin and the central area. Biopsies were processed for immunohistochemical staining.
  
  
  RESULTS
  In the outer margin CD8+ (cytotoxic T cells) and CD45RO+ (memory effector T cells) T lymphocytes invade the epidermis and in this early stage the activation markers CD2 and CD25 also show a substantial increase. The next phase, from the outer to the inner margin, shows a statistically significant increase of these markers, and especially, the cells expressing NK receptors (CD94 and CD161) show a massive increase together with a significant increase of epidermal proliferation (Ki67) and a decrease of the K10+ epidermal surface.
  
  
  CONCLUSIONS
  CD8+, CD45RO+, CD2+ and CD25+ T cells have a role in the early phase of the psoriatic process, whereas CD94- and CD161-expressing cells together with epidermal proliferation and keratinization are involved in a later phase.
authors.affiliation: Department of Dermatology, University Medical Centre St Radboud, PO Box 9101, René Descartes dreef 1, 6500 HB Nijmegen, The Netherlands.
authors.forename: W H P M
authors.initials: WH
authors.lastname: Vissers
authors.forename: C H M
authors.initials: CH
authors.lastname: Arndtz
authors.forename: L
authors.initials: L
authors.lastname: Muys
authors.forename: P E J
authors.initials: PE
authors.lastname: Van Erp
authors.forename: E M G
authors.initials: EM
authors.lastname: de Jong
authors.forename: P C M
authors.initials: PC
authors.lastname: van de Kerkhof
mesh_terms: D018450:Disease Progression; D004817:Epidermis / Q000276:immunology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007156:Immunologic Memory; D015603:Keratinocytes / Q000473:pathology; D019394:Ki-67 Antigen / Q000032:analysis; D007694:Killer Cells, Natural / Q000276:immunology; D017493:Leukocyte Common Antigens / Q000032:analysis; D011565:Psoriasis / Q000276:immunology* / Q000473:pathology; D011971:Receptors, Immunologic / Q000378:metabolism; D012867:Skin / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology
chemical_list: D019394:Ki-67 Antigen; D011971:Receptors, Immunologic; D017493:Leukocyte Common Antigens