Numbers and Distribution of Immune Cells in the Tunica Mucosa of the Small and Large Intestine of Full-Thickness Biopsies from Healthy Pet Cats

With 1 figure and 7 tables SUMMARY: In this study, CD3⁺ T lymphocytes and IgA⁺, IgG⁺ and IgM⁺ plasma cells were quantified in the tunica mucosa of the intestinal tract of 12 pet cats without gastrointestinal diseases. The study included full-thickness biopsies of the duodenum, jejunum, ileum and colon. The distribution and quantification of CD3⁺ T cells, IgA⁺, IgG⁺ and IgM⁺ plasma cells within the intestinal tunica mucosa was performed by using immunohistochemical methods and computer-aided morphometry. CD3⁺ T cells were significantly prominent in the villi and their numbers increased from duodenum to ileum but decreased towards the colon. The predominant type of plasma cells was IgA⁺ cells, followed by IgM⁺ cells. The number of IgG⁺ cells was generally low compared to the other plasma cell types investigated. The results of the vertical distribution showed that IgA⁺ and IgM⁺ plasma cells were most numerous in the lower crypt areas, whilst IgG⁺ plasma cells accumulated in the upper crypt region with a decline towards the villi and the lower crypt areas of control cats. All types of plasma cells showed a general decline from the duodenum towards the caudal sections of the intestinal tract regarding the horizontal distribution of plasma cells. This study provides a comprehensive overview on the vertical and horizontal distribution and the number of CD3⁺ T cells and IgA⁺, IgG⁺ and IgM⁺ plasma cells in the intestinal tunica mucosa of pet cats.