Cathepsin S activity is detectable in human keratinocytes and is selectively upregulated upon stimulation with interferon-gamma

Gerold Schwarz, Wolf-Henning Boehncke, Manuela Braun, Christian J Schröter, Timo Burster, Thomas Flad, Daniela Dressel, Ekkehard Weber, Heide Schmid, Hubert Kalbacher

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45 Citations (Scopus)


Keratinocytes are an integral component of the skin immune system and function as nonprofessional antigen-presenting cells in pathophysiologic conditions when they express major histocompatibility complex class II molecules, e.g., in psoriasis. In order to analyze further this function we investigated the activity of cathepsin S in comparison with cathepsins B and L. These enzymes were suggested to be involved in antigen presentation. Specific catalytic activities of these cathepsins were determined fluorometrically by hydrolysis of a synthetic substrate (Z-Phe-Arg-7-amido-4-methylcoumarin) in subcellular fractions of human keratinocytes. It was found that the human keratinocyte cell line HaCaT exhibits activities of all three cathepsins investigated. Endosomal/lysosomal compartments show highest cathepsin activities. Normal human keratinocytes in primary culture show a comparable pattern of cathepsin activities. In contrast to this, in syngeneic Epstein-Barr virus-transformed B cells the level of cathepsin B activity was found to be 10% of that in the corresponding keratinocytes, whereas the activities for cathepsins L and S were in a similar range. Interferon-gamma stimulation of primary keratinocytes and HaCaT cells resulted in a selective upregulation of the cathepsin S activity, the extent of which was very similar. The mechanism of this upregulation was demonstrated as induction at the mRNA and protein levels. This report documents that cathepsin S in human keratinocytes is selectively upregulated, in parallel to major histocompatibility complex class II molecules, in response to a pro-inflammatory cytokine. Our observations support the concept of keratinocytes functioning as nonprofessional antigen-presenting cells in states of inflammation.

Original languageEnglish
Pages (from-to)44-9
Number of pages6
JournalJournal of Investigative Dermatology
Issue number1
Publication statusPublished - Jul 2002


  • Antigen Presentation
  • Antineoplastic Agents
  • B-Lymphocytes
  • Cathepsin B
  • Cathepsin L
  • Cathepsins
  • Cell Line, Transformed
  • Cysteine Endopeptidases
  • Enzyme Activation
  • Flow Cytometry
  • Humans
  • Interferon-gamma
  • Keratinocytes
  • Lysosomes
  • Psoriasis
  • Up-Regulation
  • Journal Article
  • Research Support, Non-U.S. Gov't

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