title: Pentoxifylline inhibits T-cell adherence to keratinocytes.
abstract: In many inflammatory dermatoses leukocyte function-associated antigen-1/intercellular adhesion molecule-1 mediated T-cell/keratinocyte adhesion is considered to play an important role. Pentoxifylline (PTX), a methylxanthine derivative widely used for the symptomatic treatment of various vascular disorders, was recently found to have anti-inflammatory effects. PTX can suppress tumor necrosis factor-alpha production and function, and inhibits leukocyte-endothelial cell adherence. The aim of the present study was to investigate whether PTX also interferes with T-cell/keratinocyte binding. Peripheral blood T cells were activated with phorbol myristate acetate and co-incubated with interferon-gamma- or tumor necrosis factor-alpha-stimulated keratinocytes (SVK 14 cells) in the presence or absence of PTX. Using an enzyme-linked immuno cell adhesion assay PTX was found to inhibit T-cell/keratinocyte adhesion in a dose-dependent manner. A similar inhibition was found when PTX was replaced by isobutylmethylxanthine, another methylxanthine derivative, or by a combination of two cyclic adenosine monophosphate analogues. No major effect on T-cell/keratinocyte adherence was observed when PTX was present during the pre-incubation of keratinocyte monolayers with tumor necrosis factor-alpha or interferon-gamma prior to the adhesion assay. In keratinocyte monolayers the interferon-gamma or tumor necrosis factor-alpha induced intercellular adhesion molecule-1 expression could not be inhibited by PTX. However, when PTX was added to short-term organ cultures of normal human skin biopsies, the lipopolysaccharide- and tumor necrosis factor-alpha-induced keratinocyte intercellular adhesion molecule-1 expression was blocked completely. The interferon-gamma-induced ICAM-1 expression was not blocked by PTX. The results presented herein suggest that impaired T-cell/keratinocyte binding may be one of the mechanisms by which PTX exerts a beneficial effect in certain inflammatory dermatoses.
authors.affiliation: Department of Dermatology, Free University Hospital, Amsterdam, The Netherlands.
authors.forename: I
authors.initials: I
authors.lastname: Bruynzeel
authors.forename: L M
authors.initials: LM
authors.lastname: van der Raaij
authors.forename: T J
authors.initials: TJ
authors.lastname: Stoof
authors.forename: R
authors.initials: R
authors.lastname: Willemze
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000502:physiology; D007371:Interferon-gamma / Q000494:pharmacology; D015603:Keratinocytes / Q000737:chemistry / Q000166:cytology*; D008297:Male; D009924:Organ Culture Techniques; D010431:Pentoxifylline / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000166:cytology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D007371:Interferon-gamma; D000242:Cyclic AMP; D010431:Pentoxifylline; D015056:1-Methyl-3-isobutylxanthine