In comparison with normal individuals, sera of patients with alcoholic cirrhosis and other liver diseases had two to four times higher levels of immunoglobulin A and three to ten times higher levels of polymeric immunoglobulin A. The possible participation of the liver in the selective removal of polymeric immunoglobulin A from serum into bile was investigated by analyzing immunoglobulin A in serum and bile specimens obtained from a group of patients with T-tube drainage of the common bile duct. Gel filtration revealed three principal fractions of biliary immunoglobulin A: secretory immunoglobulin A with J chain and secretory component; polymeric immunoglobulin A associated with J chain; and monomeric immunoglobulin A devoid of J chain and secretory component. Secretory component-complexed immunoglobulin A composed only 50% or less of the total biliary immunoglobulin A. In comparison with immunoglobulin G, polymeric forms of immunoglobulin A appeared to be selectively transported into bile whereas monomeric immunoglobulin A was not. These data suggested that the liver selectively transports polymeric immunoglobulin A from serum into bile by both secretory component-dependent and -independent mechanisms. © 1982.
