title: Influence of melatonin and its precursor L-tryptophan on Th1 dependent contact hypersensitivity.
abstract: There is strong evidence that melatonin possesses immunomodulatory activity. It has been shown that it enhances the immune response, acting as a pro-inflammatory agent. It is suggested that melatonin promotes Th1-mediated immune responses by upregulating IL-12 production by antigen presenting cells. In contrast, it has also been shown that melatonin can inhibit Th1 immunity and instead promote a Th2 response. This discrepancy between different observations of the regulatory activity of melatonin on Th1 immunity encouraged us to further investigate the influence of melatonin and its precursor L-tryptophan on Th1 mediated contact hypersensitivity (CHS). Our results show that both melatonin and L-tryptophan inhibit the inflammatory response associated with CHS. Melatonin inhibited the Th1-dependent immune response by suppressing the production of IFN-gamma and IL-12 by cells in the lymph node. On the other hand treatment with L-tryptophan inhibits CHS without affecting INF-gamma production by Th1 effector cells. Observed suppression of CHS after L-tryptophan treatment is at least partly through the production of the anti-inflammatory cytokine IL-10.
authors.affiliation: Department of Human Developmental Biology, Jagiellonian University College of Medicine, ul. Kopernika 7, Kraków, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Majewska
authors.forename: K
authors.initials: K
authors.lastname: Zajac
authors.forename: M
authors.initials: M
authors.lastname: Zemelka
authors.forename: M
authors.initials: M
authors.lastname: Szczepanik
mesh_terms: D000818:Animals; D003877:Dermatitis, Contact / Q000276:immunology*; D007249:Inflammation / Q000276:immunology; D007371:Interferon-gamma / Q000096:biosynthesis; D016753:Interleukin-10 / Q000096:biosynthesis; D018664:Interleukin-12 / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D008198:Lymph Nodes / Q000378:metabolism; D008297:Male; D008550:Melatonin / Q000494:pharmacology / Q000502:physiology*; D051379:Mice; D008808:Mice, Inbred CBA; D018417:Th1 Cells / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology; D014364:Tryptophan / Q000494:pharmacology / Q000502:physiology*
chemical_list: D016753:Interleukin-10; D018664:Interleukin-12; D015847:Interleukin-4; D007371:Interferon-gamma; D014364:Tryptophan; D008550:Melatonin