Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2000
Publication Date: N/A
Interpretive Summary: Traditionally, diagnosis of intestinal diseases in dogs has been based on the evaluation of biopsies of the gut. This can provide valuable information about the architecture of the intestinal tissue, but less information about changes in specific populations of white blood cells. Changes in white blood cell populations would suggest a role for the immune esystem in intestinal disease. There are techniques available for the stud of white blood cells in the affected intestine. Previously, the study of these cells required the removal of a segment of bowel. We previously developed a method to isolate a representative sample of cells from biopsies. This minimally invasive technique can be used to study the white blood cells in the gut of client animals, and should prove useful for studying of evaluating canine intestinal disease. In the present article, we have utilized this technique on gut samples from normal dogs to examine white blood cell populations. Our study provides basic information on white blood cell populations of normal dogs which will serve as useful baseline data for comparison to client animals with intestinal diseases.
Technical Abstract: Flow cytometric analysis of the lymphocyte population of the gut could provide useful information on the immune cells present in the gut that would not be easily obtained in tissue sections. However, little is known of the normal lymphocyte population in the canine gut as determined by flow cytometry, which allows for simultaneous staining of multiple cell surface antigens and identification of specific lymphocytic subsets. Therefore, intraepithelial lymphocytes were obtained from biopsies of the healthy canine proximal small intestine and colon taken with an endoscope, and flow cytometric analysis was used to characterize the lymphocyte subsets present. Although CD3+ lymphocytes were the most abundant subset in both colon and small intestine, CD**+/CD8**- lymphocytes predominated in the proximal small intestine, whereas CD**+/CD8**- lymphocytes did in the colon. Canine CD8**+ intraepithelial lymphocytes were predominantly CD8 alpha-beta**+ in both small intestine and colon. CD4**+ intraepithelial lymphocytes were always much less numerous than CD8**+ intraepithelial lymphocytes. As in man, a majority of intraepithelial lymphocytes expressed the T-cell receptor (TCR) alpha-beta, but TCR gamma-delta was expressed by a third of intraepithelial T-cells in the proximal small intestine, and approximately 15% of those in the colon. We have showed that canine intraepithelial lymphocytes are regionally specialized, and that those from the small intestine are unique in comparison to those of other species such as man and rodents due to the large numbers of CD3**+ CD8**- intra-epithelial lymphocytes. This study provides a baseline for comparison with intraepithelial lymphocytes obtained from canine patients with intestinal disease.