Size, CD4 and CD8 marker profiles and functions of lymphocyte subpopulations in mucosal-associated lymph nodes.

We analyzed phenotypic and functional characteristics of T cell populations in mucosal-associated supramammary and mesenteric lymph nodes in goats. Here we demonstrate, by flow cytometry, quantitative differences in CD4 and CD8 T cell subsets among large and small mucosal-associated lymphocyte populations and their differential regulatory activities on resident lymph node B cells stimulated with Staphylococcus aureus Cowan I or pokeweed mitogen. The CD4/CD8 T cell ratio was lower in mesenteric lymph nodes (1.46) when compared to that of supramammary lymph nodes (2.18). Analysis of large and small lymphocyte subpopulations from lymph nodes showed nearly 62% of the lymphocytes from mesenteric lymph nodes being of large cell phenotype with CD4/CD8 ratios of 1.34. In contrast, large cell subpopulations in supramammary lymph nodes showed a significantly lower number (50%) with a higher CD4/CD8 ratio of 2.05. Functionally, mesenteric lymph node T cells, isolated by nylon wool, showed heightened suppressive activity in mitogen-driven B cell proliferation responses, whereas T cells from supramammary lymph nodes were stimulatory. These findings clearly demonstrate distinctive functional properties between resident T cell populations of supramammary and mesenteric lymph nodes, suggesting that different proportions of T cell subsets in these nodes are activated and thus regulate regional immune responses via different pathways.