Microscopic Observation of Lymphocyte Dynamics in Rat Peyer's Patches

Naïve lymphocytes recirculate from the blood to the lymphoid tissues under physiological condition and it is commonly recognized as an important phenomenon in the gut immunity. The stroma of secondary lymphoid organs, such as Peyer's patches (PPs) or mesenteric lymph nodes, are where naïve lymphocytes sense antigens. Naïve lymphocytes circulate through the bloodstream to reach high endothelial venules, the portal of entry into PPs. Some immunomodulators are estimated to influence lymphocyte migration, but the precise evaluation of microcirculation dynamics is very difficult, and establishing a method to observe lymphocyte migration in vivo can contribute to the clarification of the precise mechanisms. We refined the method of collecting lymphocytes from the lymph duct and observing the detailed dynamics of gut-tropic lymphocytes in rat PPs. We chose confocal laser scanning microscopy to observe rat PPs in vivo and recorded it using time-lapse photography. We can now obtain clear images that can contribute to the analysis of lymphocyte dynamics.