Immune cell populations within the duodenal mucosa of dogs with enteropathies

The mucosal immune system may play a critical role in the pathogenesis of s mall intestinal enteropathies. The aim of the current study was to assess m ucosal immune cell populations in dogs with inflammatory bowel disease (IBD ); idiopathic antibiotic-responsive diarrhea (ARD), and adverse reactions t o food (FR). Endoscopic biopsies were performed of the duodenum of dogs wit h these conditions and from a group of dogs without enteric disease. Additi onal control samples were collected after death from other dogs that did no t have evidence of,enteric disease. Immunohistochemistry and computer-aided morphometry were used to assess the distribution of immune cell subsets in both lamina propria and intestinal epithelium. Compared with controls, dog s with ARD had increased numbers of lamina propria immunoglobulin (Ig) AC p lasma cells and CD4(+) cells. More marked alterations were noted in dogs wi th LED, with significant increases in lamina propria IgG(+) plasma cells, T cells (CD3(+)), CD4(+) cells, macrophages, and neutrophils, but with reduc ed mast cell numbers. Increased intraepithelial CD3+ T cells were also pres ent in the dogs with IBD, compared with controls. However, lamina propria a nd epithelial populations were unaltered in dogs with FR when compared with controls. The altered mucosal immune cell populations observed in dogs wit h ARD or IBD may reflect an underlying immunologic pathogenesis in these di sorders.