Phenotypic Characterization of Canine Intestinal Intraepithelial Lymphocytes in Dogs with Inflammatory Bowel Disease.

Background Many dogs suffering from inflammatory bowel disease ( IBD) are presented to veterinary clinics. These patients are diagnosed based on a history of chronic gastrointestinal signs and biopsy-confirmed histopathologic intestinal inflammation. Intestinal intraepithelial lymphocytes ( IEL) are part of the first line of defense in the gastrointestinal immune system. Alterations in IEL subsets may play a role in the pathogenesis of IBD. Hypothesis The aim of this study was to characterize the phenotypes of IEL in dogs with IBD compared with healthy control dogs. Animals Intestinal intraepithelial lymphocytes subpopulations of control dogs (n = 5) obtained from endoscopic biopsies ( EB) were compared to those obtained from full thickness biopsies ( FTB) on the same day. In addition, the phenotypes of IEL from FTB of control dogs (n = 10) were compared with EB of IBD dogs (n = 10). Each participant was scored clinically using the canine inflammatory bowel disease activity index ( CIBDAI), and all samples were graded histopathologically. Three-color flow cytometry of isolated IEL was performed using monoclonal antibodies against T- and B-lymphocyte subpopulations. Results No significant differences in the composition of IEL subpopulations were found in control dogs based on method of biopsy. The IBD dogs had significantly higher CIBDAI and histopathologic scores compared with control dogs and their IEL contained a significantly higher frequency TCRγδ T-cells. Conclusions and Clinical Importance Endoscopic biopsies provide suitable samples for 3-color flow cytometry when studying canine intestinal IEL and IBD patients show significant changes of major T-cell subsets compared to healthy control dogs. [ABSTRACT FROM AUTHOR]