Neutrophil mediated and IgA dependent antibacterial immunity against enteropathogenic Escherichia coli in the porcine intestinal mucosa.
The role of polymorphonuclear neutrophils (PMN) in the antibacterial immunity against enteropathogenic Escherichia coli (EEC) 0:149 in the porcine intestine was studied using intestinal Thiry-Vella loop (T-V loop) as a model. Intraluminal immunizations of T-V loops resulted in elevated levels of immunoglobulin A (IgA) anti-EEC 0:149 antibody in the loop secretions, an infiltration of PMN in the lumen of the loops and an increase in the concentrations of lactoferrin (LF), lysozyme (LY), cationic proteins (CP), and a specific bactericidal response in the immunized loops. PMN were observed by electron microscopy (EM) to be actively phagocytic in the lumen of the immune loops. EM observations of loop fluids as well as the abrogating effect of iron on the in vivo bactericidal response strongly suggest that the pMN played an important role in the bactericidal response in the loops against EEC. In addition to phagocytosis by PMN and subsequent intracellular killing, disintegration of PMN in the lumen of the loops and extracellular killing of EEC by the antibacterial products of PMN such as LF, LY and CP, with and/or without synergistic effect of IgA antibodies, also contribute to the bactericidal response of the immunized loops.
D000818:Animals; D004926:Escherichia coli / Q000276:immunology; D004927:Escherichia coli Infections / Q000276:immunology / Q000662:veterinary*; D007070:Immunoglobulin A / Q000276:immunology*; D007410:Intestinal Diseases / Q000276:immunology / Q000662:veterinary*; D007413:Intestinal Mucosa / Q000276:immunology*; D009504:Neutrophils / Q000276:immunology*; D013552:Swine; D013553:Swine Diseases / Q000276:immunology*
D007070:Immunoglobulin A