title: Cellular and humoral immune responses in atrophic lymphocytic pancreatitis in German shepherd dogs and rough-coated collies.
abstract: The most common cause for the clinical signs of exocrine pancreatic insufficiency (EPI) in dogs is pancreatic acinar atrophy (PAA). In the subclinical phase of EPI, before total atrophy occurs, exocrine pancreas is affected by infiltrative lymphocytic inflammation, which gradually leads to selective destruction and atrophy of the acinar tissue.Here, we analyzed the role of cell-mediated and humoral immune mechanisms in the pathogenesis of atrophic lymphocytic pancreatitis in German shepherd dogs and rough-coated collies. Pancreas biopsies and serum samples were obtained from 12 dogs with subclinical EPI (SEPI), 13 dogs with clinical EPI and 13 healthy control dogs. Immunohistochemical analysis showed that, in the subclinical phase, the majority of the infiltrating lymphocytes were T-cells with an almost equal number of CD4+ 'T-helper' and CD8+ 'cytotoxic' T-lymphocytes. The distribution of the two lymphocyte subsets was different. Typically, the CD4+ cells were present in large cellular infiltrates in the affected parenchyma, and the scattered CD8+ cells had infiltrated both the affected and the normal parenchyma. In sections where destruction of acinar parenchyma was present, the CD8+ T-cells were predominant. In cases of marked T-cell infiltration, CD79+ B-lymphocytes and plasma cells, and lysozyme-positive macrophages were also detected. Lymphoid follicle germinal centers with a majority of cells staining positively for CD79 were found. The lymphocytic infiltration in the totally atrophic tissue of dogs with clinical EPI was less prominent. Indirect immunofluorescence staining showed serum antibodies reacting weakly with pancreatic acinar cells in five out of nine dogs with subclinical and three out of 10 dogs with clinical EPI, but not in the control dogs. The results suggest that the tissue destruction is largely T-cell-mediated, although the presence of numerous B-lymphocytes and pancreas-specific antibodies in the sera of some dogs indicate that humoral mechanisms are also involved. In conclusion, this study suggests that the atrophic lymphocytic pancreatitis in German shepherds and rough-coated collies is an autoimmune disease.
authors.affiliation: Department of Clinical Veterinary Sciences, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 57, FIN-00014 Helsinki, Finland. maria.wiberg@helsinki.fi
authors.forename: M E
authors.initials: ME
authors.lastname: Wiberg
authors.forename: S A
authors.initials: SA
authors.lastname: Saari
authors.forename: E
authors.initials: E
authors.lastname: Westermarck
authors.forename: S
authors.initials: S
authors.lastname: Meri
mesh_terms: D000818:Animals; D000917:Antibody Formation; D015703:Antigens, CD / Q000032:analysis; D001323:Autoantibodies / Q000097:blood; D001797:Blood Protein Electrophoresis / Q000662:veterinary; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D051925:CD79 Antigens; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D004283:Dog Diseases / Q000276:immunology*; D004285:Dogs; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000662:veterinary; D007111:Immunity, Cellular; D016130:Immunophenotyping / Q000662:veterinary; D008297:Male; D008856:Microscopy, Fluorescence / Q000662:veterinary; D010195:Pancreatitis / Q000276:immunology / Q000662:veterinary*; D011947:Receptors, Antigen, B-Cell / Q000032:analysis
chemical_list: D015703:Antigens, CD; D001323:Autoantibodies; D051925:CD79 Antigens; D011947:Receptors, Antigen, B-Cell