Secretory immunoglobulin a blocks hypoxia-augmented bacterial passage across Madin-Darby canine kidney cell monolayers

Objective: To study the relative impact of previous hypoxic exposure and the addition of secretory immunglobulin A (IgA) on bacterial translocation. Design: In vitro randomized experimental study. Materials and Methods: Transfected Madin-Darby canine kidney epithelial cells were grown as monolayers in a two-chamber tissue culture system. Stationary growth phase Escherichia coli M14 were inoculated in the apical chamber with medium or medium containing polymeric secretory IgA. Tissue culture dishes were then placed in a 21 or 5% O-2 incubator environment for 90 minutes followed by a 21% O-2 environment. Medium from the basal compartment was then obtained at timed intervals for bacterial culture. Measurement and Main Results: Bacterial translocation increased with time in co-culture. previous hypoxic exposure augmented translocation across the monolayers. The addition of IgA blocked translocation under both normoxic and hypoxic conditions. Conclusions: Secretory IgA is important in mucosal defense under both normal and shock conditions.