Complement in local biliary tract defense: dissociation between bile complement and acute phase reactants in cholecystitis.

Biliary complement concentrations and activity are lower in patients with infected bile than in those with sterile bile in cholecystitis. Plasma complement is increased during the acute phase response to inflammation. To determine whether low biliary complement in infected bile is a specific response to biliary tract infection or part of a general systemic reaction, we analyzed bile complement proteins (C3 and C4) and activity (C4H50) and acute phase reactants fibronectin, C-reactive protein, and alpha 1-antitrypsin concentrations in acute and chronic cholecystitis. Results were correlated with bile cultures and gallbladder histology using the Wilcoxon rank sum test. While biliary C3, C4, and C4H50 were significantly lower in infected bile than in sterile bile, none of the acute phase reactants were different. The biliary acute phase reactants were all significantly higher in acute cholecystitis than in chronic disease, but there was no difference in the biliary C3, C4, or C4H50 levels. There was no clear relationship between plasma levels of complement and the acute phase reactants. The dissociation between biliary complement and acute phase reactants indicates that bile complement is not a reflection of a systemic reaction to inflammation. We propose that biliary complement is a specific host defense mechanism against bacterial infection in the biliary tract.