Morphological Changes in Mesenteric Lymph Nodes and Lymphocyte Subpopulation Composition in Experimental Ulcerative Colitis

Morphological changes in the mesenteric lymph nodes of male C57Bl/6 mice and subpopulation composition of lymphocytes in these nodes were studied in experimental acute and chronic ulcerative colitis induced by sodium dextran sulfate. Acute and chronic ulcerative colitis was associated with the development of reactive changes in the mesenteric lymph nodes. These changes were of mixed type and were characterized by follicular hyperplasia and sinus reaction. The content of CD19 + B cells in the mesenteric lymph nodes decreased in acute ulcerative colitis, while the content of CD3 + CD8 + cytotoxic T cells increased, which presumably reflected activation of Th1 reactions. The increase in the count of CD4 + CD25 + FOXP3 + regulatory T cells and CD3 + CD8 + cytotoxic T cells was due to intensive migration of lymphocytes from the thymus and the colonic compartment of the local immune system. Chronic ulcerative colitis was associated with higher levels of CD19 + B cells and CD3 + CD4 + T helper cells in the mesenteric lymph nodes, which was characteristic of adoptive immunity reactions and chronization of the inflammatory process.