Studies on the origins of biliary immunoglobulins in rats

This study was designed to investigate the origins of biliary immunoglobulins in rats. Natural antibodies to species of Lactobacillus and Staphylococcus were detected in blood, bile, and lymph, with predominant activity being associated with immunoglobulin A in lymph and bile and with immunoglobulins M and G in blood. Six hours after thoracic duct cannulation, serum immunoglobulins G, M, and A had fallen to 60%, 65%, and 40%, respectively, of the preoperative levels, whereas the level of total and specific immunoglobulin A in bile was reduced to 25% with no significant decline of immunoglobulin G. Thoracic duct occlusion caused a similar selective reduction in biliary immunoglobulin A. It is calculated that 50% of thoracic duct lymph immunoglobulin A entering the blood is secreted in bile. Synthesis of immunoglobulins M, G, and A in the liver was established by the detection of antibody-secreting cells. It is proposed that the major part of biliary immunoglobulin A is derived from intestinal lymphoid tissues and that a portion of the remainder, as well as part of biliary immunoglobulins M and G, results from local synthesis.