title: Lack of evidence for TARC/CCL17 production by normal human keratinocytes in vitro.
abstract: BACKGROUND
  thymus and activation-regulated chemokine (TARC)/CCL17 is a CC chemokine that selectively attracts Th2-type lymphocytes. Immunohistochemical analyses have revealed that TARC is expressed in the epidermal keratinocytes of atopic dermatitis (AD), suggesting TARC involvement in the pathogenesis of the disease. However, keratinocyte TARC production has been described only in the transformed keratinocyte cell line HaCaT.
  
  
  OBJECTIVE
  to examine TARC production in normal human epidermal keratinocytes (NHEK) in vitro.
  
  
  METHODS
  the expression of TARC mRNA and protein were examined in NHEK and HaCaT cells stimulated with various cytokines.
  
  
  RESULTS
  stimulation with inflammatory cytokines, including interleukin (IL)-1, IL-4, IL-6, IL-10, interferon (IFN)-alpha, IFN-beta, IFN-gamma, and tumor necrosis factor (TNF)-alpha failed to induce TARC mRNA expression in NHEK. However, stimulation with IFN-gamma and TNF-alpha together enhanced expression slightly. ELISA analysis failed to detect TARC protein in NHEK culture supernatant, even following stimulation with IFN-gamma and TNF-alpha. In contrast, HaCaT cells produced TARC protein even without stimulation of cytokines.
  
  
  CONCLUSIONS
  these results indicate that production of TARC by HaCaT cells is a phenomenon specific to the cell line and the observation on TARC in HaCaT cells can not be generalized. NHEK do not produce TARC protein in vitro.
authors.affiliation: Department of Dermatology, Ehime University School of Medicine, Shitsukawa, Shigenobucho, Onsengun, Ehime 791-0295, Japan.
authors.forename: Teruko
authors.initials: T
authors.lastname: Tsuda
authors.forename: Mikiko
authors.initials: M
authors.lastname: Tohyama
authors.forename: Kenshi
authors.initials: K
authors.lastname: Yamasaki
authors.forename: Yuji
authors.initials: Y
authors.lastname: Shirakata
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yahata
authors.forename: Sho
authors.initials: S
authors.lastname: Tokumaru
authors.forename: Koji
authors.initials: K
authors.lastname: Sayama
authors.forename: Koji
authors.initials: K
authors.lastname: Hashimoto
mesh_terms: D002478:Cells, Cultured; D054414:Chemokine CCL17; D019742:Chemokines, CC / Q000096:biosynthesis* / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: C106230:CCL17 protein, human; D054414:Chemokine CCL17; D019742:Chemokines, CC; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma