AN IN-VITRO MODEL TO ASSESS MUCOSAL IMMUNE FUNCTION AND BACTERIAL TRANSLOCATION

The importance of secretory immunoglobulin A (IgA) on intestinal barri er function has gained increasing acceptance. However, due to the comp lexity of the intestinal microenvironment, the relative role of secret ory IgA (sIgA) in mucosal defense has been difficult to study in vivo. Polarized Madin-Darby canine kidney (MDCK) epithelial cells expressin g the complementary DNA (cDNA) for the polymeric Ig receptor were grow n as monolayers in an in vitro two-chamber cell culture system to stud y the impact of sIgA on bacterial translocation (BT), Polymeric sIgA o r media alone was added to the apical chambers of cell monolayers foll owed by apical inoculation with bacteria, The basal compartment was sa mpled at timed intervals thereafter to determine BT. Bacterial passage across the MDCK epithelial cell monolayers occurred in a time and bac terial inoculum concentration gradient, Addition of sIgA led to signif icant reductions in BT across the epithelial cell monolayers. This is a useful model for further investigation on the role of sIgA in intest inal barrier function. (C) 1997 Academic Press.