INTESTINAL IMMUNIZATION WITH ESCHERICHIA-COLI PROTECTS RATS AGAINST ESCHERICHIA-COLI INDUCED CHOLANGITIS

Background-Cholangitis, an infection of the biliary tract, is most com monly caused by Gram negative bacteria, particularly Escherichia coli, Factors governing the severity of cholangitis, including the role of biliary IgA, are poorly understood. Aims-The aim of this work was to f ind out if biliary IgA directed against E coli protects rats against h epatobiliary infection with E coli. Subjects-Male Sprague-Dawley rats weighing 210-350 grams were used in all of the experiments. Methods-At laparotomy, rats were immunised by injecting killed E coli or normal saline (controls) into Peyer's patches, With or without subsequent ant igenic boosting (by oral administration of killed E coli), bile was co llected at a second laparotomy, and rats were infected by introducing viable E coli into the bile duct. Production of IgA anti-E coli antibo dy was measured by enzyme linked immunosorbent assay of bile, and the presence. of hepatobiliary infection was determined by quantitative cu lture of liver homogenates. Results-Systemic infection was present in six of 12 control rats and in one of 24 immunised rats (p=0.005) after death. There was an inverse correlation between immunisation and E co li colony counts in cultured liver homogenates (p=0.024). Conclusion-T he findings suggest that biliary IgA directed against E coli protected rats against hepatobiliary E coli infection and systemic sepsis.