Lymphocyte subpopulations in rat lungs and Peyer's patches

The distribution of lymphocyte subpopulations in rat lungs and Peyer's patches was examined by immunofluorescent microscopy of frozen sections and single cell suspensions. The results showed that there are differences in the lymphocyte subpopulations in these tissues. More B cells were present in Peyer's patches (56.5%) than in lung (15.2%), and, conversely, there were more T cells (W3/13+) in lung (61.7%) than in Peyer's patches (20.7%). In addition, the great majority of T cells found in Peyer's patches were W3/25+ cells (the phenotypic marker of helper T cells in the rat). This was not the case in lung, where a maximum of 46% of T cells were W3/25+. Alveolar macrophages (defined by adherence to plastic and nonspecific esterase activity) did not express W3/13 or W3/25 antigens.