An in vitro model to assess mucosal immune function and bacterial translocation

The importance of secretory immunoglobulin A (IgA) on intestinal barrier function has gained increasing acceptance. However, due to the complexity of the intestinal microenvironment, the relative role of secretory IgA (sIgA) in mucosal defense has been difficult to study in vivo. Polarized Madin-Darby canine kidney (MDCK) epithelial cells expressing the complementary DNA (cDNA) for the polymeric Ig receptor were grown as monolayers in an in vitro two-chamber cell culture system to study the impact of sIgA on bacterial translocation (BT), Polymeric sIgA or media alone was added to the apical chambers of cell monolayers followed by apical inoculation with bacteria, The basal compartment was sampled at timed intervals thereafter to determine BT. Bacterial passage across the MDCK epithelial cell monolayers occurred in a time and bacterial inoculum concentration gradient, Addition of sIgA led to significant reductions in BT across the epithelial cell monolayers. This is a useful model for further investigation on the role of sIgA in intestinal barrier function. (C) 1997 Academic Press.