title: CD4+CD25+ T cells expressing FoxP3 in Icelandic horses affected with insect bite hypersensitivity.
abstract: Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis caused by bites of midges from the genus Culicoides. We have shown previously that peripheral blood mononuclear cells (PBMC) from IBH-affected horses produce higher levels of IL-4 and lower levels of IL-10 and TGF-β1 than those from healthy horses, suggesting that IBH is associated with a reduced regulatory immune response. FoxP3 is a crucial marker of regulatory T cells (Tregs). Here we have determined the proportion of CD4(+)CD25(+)FoxP3(+) T cells by flow cytometry in PBMC directly after isolation or after stimulation with Culicoides extract or a control antigen (Tetanus Toxoid). There were no differences between healthy and IBH horses either in the proportion of FoxP3(+)CD4(+)CD25(+) cells in freshly isolated PBMC or in the following stimulation with Tetanus Toxoid. However, upon stimulation of PBMC with the allergen, expression of FoxP3 by CD4(+)CD25(+high) and CD4(+)CD25(+dim) cells was significantly higher in healthy than in IBH horses. Addition of recombinant IL-4 to PBMC from healthy horses stimulated with the allergen significantly decreased the proportion of FoxP3 expressing cells within CD4(+)CD25(+high). These results suggest that IBH is associated with a decreased number of allergen-induced Tregs. This could be a consequence of the increased IL-4 production by PBMC of IBH-affected horses.
authors.affiliation: Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland. eman.hamza@vetsuisse.unibe.ch
authors.forename: Eman
authors.initials: E
authors.lastname: Hamza
authors.forename: Falko
authors.initials: F
authors.lastname: Steinbach
authors.forename: Eliane
authors.initials: E
authors.lastname: Marti
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002519:Ceratopogonidae / Q000276:immunology*; D005434:Flow Cytometry / Q000662:veterinary; D051858:Forkhead Transcription Factors / Q000096:biosynthesis / Q000276:immunology*; D006734:Horse Diseases / Q000276:immunology*; D006736:Horses; D006967:Hypersensitivity / Q000276:immunology / Q000662:veterinary*; D007299:Insect Bites and Stings / Q000276:immunology / Q000662:veterinary*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000276:immunology*
chemical_list: D051858:Forkhead Transcription Factors