title: The role of histamine-like receptors in immunosuppression of delayed hypersensitivity induced by cis-urocanic acid.
abstract: The cis-isomer of urocanic acid (UCA) has been shown previously to mimic the effect of ultraviolet B (UVB) irradiation in suppressing delayed hypersensitivity (DH) responses to virus in a murine model of herpes simplex virus (HSV) infection. Cimetidine, an H2 receptor antagonist, and terfenadine, an H1 receptor antagonist, abrogated the suppression of DH to HSV induced by cis-UCA, leading to the suggestion that histamine-like receptors may be involved in the mechanism of action of cis-UCA on immune responses. In the present study, cis and trans-isomers of 4 UCA analogues (1- and 2-imidazoyl-acrylic acid), and (2- and 3-pyridyl-acrylic acid) were tested for their ability to suppress DH to HSV in infected mice, and only cis-2-pyridyl-acrylic acid was effective. Second, an H2 and H3 agonist were similarly tested: the former was suppressive and the latter had no effect. Third, an H3 receptor antagonist, thioperamide, did not seem to abrogate the suppression of DH induced by cis-UCA. These results substantiate a role for H1 and H2-like receptors, but probably not H3 receptors, in cis-UCA induced immunosuppression.
authors.affiliation: Department of Medical Microbiology, University of Edinburgh Medical School, United Kingdom.
authors.forename: J W
authors.initials: JW
authors.lastname: Gilmour
authors.forename: M
authors.initials: M
authors.lastname: Norval
authors.forename: T J
authors.initials: TJ
authors.lastname: Simpson
authors.forename: K
authors.initials: K
authors.lastname: Neuvonen
authors.forename: P
authors.initials: P
authors.lastname: Pasanen
mesh_terms: D000818:Animals; D005260:Female; D006561:Herpes Simplex / Q000276:immunology*; D017442:Histamine Agonists / Q000494:pharmacology; D006633:Histamine Antagonists; D006968:Hypersensitivity, Delayed / Q000276:immunology*; D007108:Immune Tolerance / Q000187:drug effects / Q000502:physiology*; D008761:Methylhistamines / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D010880:Piperidines / Q000494:pharmacology; D011968:Receptors, Histamine / Q000502:physiology*; D014560:Urocanic Acid / Q000031:analogs & derivatives / Q000494:pharmacology*
chemical_list: D017442:Histamine Agonists; D006633:Histamine Antagonists; D008761:Methylhistamines; D010880:Piperidines; D011968:Receptors, Histamine; D014560:Urocanic Acid; C052075:thioperamide