title: Increased IL-4 and decreased regulatory cytokine production following relocation of Icelandic horses from a high to low endoparasite environment.
abstract: Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis of horses caused by bites of Culicoides spp. IBH does not occur in Iceland where Culicoides are absent. However, following importation into continental Europe where Culicoides are present, >or=50% of Icelandic horses (1st generation) develop IBH but <or=10% of their offspring born in Europe (2nd generation) do so. Recently, we showed that PBMC from 1st generation horses produce more IL-4 than 2nd generation horses. Since helminths and allergens induce Th2 responses, we investigated whether horses domiciled in Iceland are Th2-biased, and whether this is determined by helminth infection. We compared the parasite burden and T cell responses between Icelandic horses living in Iceland or Switzerland. Horses in Iceland have higher faecal egg counts, higher tapeworm-specific IgG(T) levels and higher total serum IgE levels than horses in Switzerland. Nevertheless, horses in Iceland displayed a low proportion of IL-4-producing cells in PBMC cultures after polyclonal or parasite extracts stimulation. No IL-4-producing cells were found in PBMC from horses after stimulation by Culicoides extract. Addition of anti-IL-10 and anti-TGF-beta1 to PBMC cultures of horses in Iceland increased the proportion of IL-4-producing cells after polyclonal or parasite antigens stimulation but not stimulation with Culicoides extract. This paralleled the high levels of IL-10 and TGF-beta1 found in supernatants from PBMC cultures of horses in Iceland. Collectively, horses living in Iceland have a high parasite burden but low IL-4 production. This supports the hypothesis that heavy helminth infections have a suppressive effect on IL-4 production mediated by IL-10 and TGF-beta1.
authors.affiliation: Department of Clinical Research, Vetsuisse Faculty, University of Bern, Bern, Switzerland. eman.hamza@kkh.unibe.ch
authors.forename: Eman
authors.initials: E
authors.lastname: Hamza
authors.forename: Sigurbjörg
authors.initials: S
authors.lastname: Torsteinsdottir
authors.forename: Matthías
authors.initials: M
authors.lastname: Eydal
authors.forename: Caroline F
authors.initials: CF
authors.lastname: Frey
authors.forename: Jelena
authors.initials: J
authors.lastname: Mirkovitch
authors.forename: Marja
authors.initials: M
authors.lastname: Brcic
authors.forename: Bettina
authors.initials: B
authors.lastname: Wagner
authors.forename: A Douglas
authors.initials: AD
authors.lastname: Wilson
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Jungi
authors.forename: Eliane
authors.initials: E
authors.lastname: Marti
mesh_terms: D000818:Animals; D002519:Ceratopogonidae / Q000276:immunology*; D005243:Feces / Q000469:parasitology; D005434:Flow Cytometry / Q000662:veterinary; D006374:Helminthiasis, Animal / Q000097:blood / Q000276:immunology / Q000469:parasitology; D006376:Helminths / Q000276:immunology; D006734:Horse Diseases / Q000276:immunology* / Q000469:parasitology*; D006736:Horses; D007055:Iceland; D007073:Immunoglobulin E / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007299:Insect Bites and Stings / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D015847:Interleukin-4 / Q000096:biosynthesis / Q000097:blood / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D010270:Parasite Egg Count / Q000662:veterinary; D018418:Th2 Cells / Q000276:immunology*
chemical_list: D007074:Immunoglobulin G; D015847:Interleukin-4; D007073:Immunoglobulin E