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Clonality testing as complementary tool in the assessment of different patient groups with canine chronic enteropathy

Luckschander-Zeller, Nicole, Hammer, Sabine E., Ruetgen, Barbara C., Tichy, Alexander, Thalhammer, Johann G., Haas, E., Richter, Barbara, Welle, Monika, Burgener, Iwan A.
Veterinary immunology and immunopathology 2019 v.214 pp. 109893
B-lymphocytes, Beagle, T-lymphocytes, biopsy, colon, diarrhea, dogs, duodenum, genes, histopathology, inflammatory bowel disease, lymphoma, patients, retrospective studies
Differentiation between canine chronic enteropathy (CCE) and intestinal lymphoma is a diagnostic challenge as histopathology might fail to yield unequivocal results. Detection of clonal rearrangements of the T-cell-receptor gamma (TCRG) chain and IG heavy chain (IGH) V-J genes offer a useful solution. In this retrospective study, histopathology samples of 35 CCE patients and 7 healthy Beagle dogs underwent clonality testing. Patients suffered either from inflammatory bowel disease (IBD), food responsive diarrhea (FRD) or protein loosing enteropathy secondary to IBD (PLE/IBD). Healthy Beagles served as controls (CO).Canine IBD activity index (CIBDAI) and histopathological WSAVA–grading differed significantly (p<0.001) between groups. CIBDAI improved significantly after appropriate therapy (p < 0.0001). Intestinal biopsies of all CO showed polyclonal patterns for B- and T-cell primers. All samples from CCE patients showed polyclonal patterns for the B-cell primers. Targeting TCRG, 4 patients showed a monoclonal or oligoclonal pattern of the lymphocytic infiltrates in the duodenum and/or colon. Clinical improvement was observed in all dogs. Although a small cell lymphoma cannot be excluded in view of the short follow up duration, a false positive result, in the sense of a canonical rearrangement or unspecific amplification due to a antigenic stimulation in a non-neoplastic inflammatory process is possible.