title: Ontogeny and disease responses of Langerhans-like cells in lymphoid tissues of salmonid fish.
abstract: The ontogeny and disease responses of Langerhans-like cells within lymphoid tissues of Atlantic salmon, Salmo salar, and rainbow trout, Oncorhynchus mykiss, were investigated. These cells were studied in situ with the use of two markers: the ultrastructural presence of Birbeck-like granules and immunohistochemistry with an antibody against human langerin/CD207 that cross-reacts with salmonid tissues. The appearance of Birbeck-like granules was observed in rainbow trout at 2 weeks post-hatch (PH) in the thymus and anterior kidney prior to the development of the spleen. Spleen first appeared at 3 weeks PH in both Atlantic salmon and rainbow trout, and Birbeck-like granules were observed within cells of the newly developed spleens. The cross-reactivity of langerin as seen by immunohistochemistry was not clearly observed in kidney and spleen until 9 weeks PH, when a strong cytoplasmic reaction was observed. To study langerin-positive cells in spleen and kidney during disease, microsporidial gill disease (MGD) in rainbow trout was used as a known disease model inducing a strong cell-mediated adaptive immune response. Langerin-positive cells in healthy fish were seen predominantly in the spleen, and only low numbers were present in the anterior kidney. During MGD, langerin-positive cell numbers were elevated in the anterior kidney and were significantly higher during 5, 6, and 10 weeks post-exposure (PE) compared with healthy control tissue. During MGD, the distribution of langerin-positive cells in the spleen and anterior kidney shifted from having significantly higher numbers of cells in the spleen than in the kidney in controls and at 1 and 4 weeks PE to having a similar distribution of the cells in the two organs at 2, 3, 5, and 6 weeks PE. By 10 weeks PE, significantly higher numbers of langerin-positive cells occurred in the anterior kidney compared with the spleen.
authors.affiliation: Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Canada. Jan.Lovy@dfo-mpo.gc.ca
authors.forename: Jan
authors.initials: J
authors.lastname: Lovy
authors.forename: Gayle P
authors.initials: GP
authors.lastname: Savidant
authors.forename: Glenda M
authors.initials: GM
authors.lastname: Wright
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D002478:Cells, Cultured; D003594:Cytoplasmic Granules / Q000276:immunology; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology; D029941:Fish Proteins / Q000276:immunology*; D006801:Humans; D007801:Langerhans Cells / Q000276:immunology* / Q000473:pathology; D037181:Lectins, C-Type / Q000276:immunology; D037601:Mannose-Binding Lectin / Q000276:immunology; D016814:Microsporidia; D016881:Microsporidiosis / Q000276:immunology* / Q000382:microbiology / Q000662:veterinary*; D017686:Oncorhynchus mykiss / Q000276:immunology* / Q000382:microbiology; D020317:Salmo salar / Q000276:immunology* / Q000382:microbiology; D013154:Spleen / Q000276:immunology* / Q000382:microbiology
chemical_list: D015703:Antigens, CD; D029941:Fish Proteins; D037181:Lectins, C-Type; D037601:Mannose-Binding Lectin