title: Cell-kinetic evidence for increased recruitment of cycling epidermal cells in psoriasis: the ratio of histone and Ki-67 antigen expression is constant.
abstract: BACKGROUND
  One of the hallmarks of the psoriatic plaque is increased epidermal proliferation. Whether this is the result of an increased recruitment of cycling epidermal cells or a decrease in cell cycle time has been a matter of debate for years.
  
  
  OBJECTIVE
  Calculating cell-kinetic information from the number of S phase cells in psoriasis by in situ hybridisation using a histone probe and the number of cycling epidermal cells by immunohistochemistry using the MIB-1 antibody.
  
  
  METHODS
  Immunohistochemistry and non-isotopic in situ hybridisation were performed on serial sections of 33 untreated psoriatic samples and 14 tacalcitol-treated samples.
  
  
  RESULTS
  The labelling index (number of cells in S phase/number cycling cells per millimetre length of section) in psoriatic untreated as well as in treated plaques is 16%. The amount of S phase cells in our experiment is equal compared with the number of cells in S phase as determined by BrdU incorporation.
  
  
  CONCLUSIONS
  Using this direct approach to study cell-kinetic behaviour of psoriatic skin, we reconfirm that the psoriatic abnormality is due to a defect in the G(0)-G(1) recruitment mechanism (by increased recruitment of G(0) cells), a decrease in apoptosis or an increase in the number of cell divisions in the transit-amplifying compartment, rather than a reduction in the cell cycle time.
authors.affiliation: Department of Dermatology, University Hospital Nijmegen, The Netherlands. f.castelijns@derma.azn.nl
authors.forename: F A
authors.initials: FA
authors.lastname: Castelijns
authors.forename: M J
authors.initials: MJ
authors.lastname: Gerritsen
authors.forename: P E
authors.initials: PE
authors.lastname: van Erp
authors.forename: P C
authors.initials: PC
authors.lastname: van de Kerkhof
mesh_terms: D002453:Cell Cycle; D000078404:Epidermal Cells; D004817:Epidermis / Q000737:chemistry; D015870:Gene Expression; D006657:Histones / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D019394:Ki-67 Antigen / Q000096:biosynthesis; D007700:Kinetics; D011565:Psoriasis / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016196:S Phase; D012867:Skin / Q000737:chemistry / Q000378:metabolism / Q000473:pathology
chemical_list: D006657:Histones; D019394:Ki-67 Antigen; D012333:RNA, Messenger