Figure 5. Characterization of Caco-2 cell/mouse Peyer's patch lymphocyte co-cultures.

A) Transmission electron micrograph of a Caco-2 cell monolayer co-cultured for three days with mouse Peyer's patch lymphocytes. A lymphocyte (L) can be seen within the Caco-2 monolayer. The epithelial cells above the lymphocyte exhibit a more sparse and less organized brush-border as well as less dense cytoplasm compared to neighboring epithelial cells not in contact with lymphocytes. B) TEER is unchanged in the co-cultures, confirming that tight junctions remain intact. Results of two experiments are shown, each with triplicate wells. C) Alkaline phosphatase activity assayed using p-nitrophenylphosphate (2.86 mM) as substrate. Absorbances at 405nm after a 1.5h incubation at 37°C were 0.454 ± 0.018 and 0.603 ± 0.024 (mean ± SD) for co-cultures and Caco-2 monocultures, respectively (n=6; p<0.0001). D) Transcytosis of fluorescent 0.2 μm microbeads from apical to basolateral medium, assessed by fluorescence microscopy. Images representative of two experiments, n=3-6.