Demonstration of IgA and secretory component in human hepatocytes.

By the immunoperoxidase technique, immunoglobulin A(IgA) was demonstrated in 50% of human hepatocytes. The positively stained cells showed a tendency towards periportal clustering. Very few plasma cells were identified in the liver. The intrahepatocyte IgA is most probably derived from serum and on its way to the bile ducts. Secretory component (SC) had the same distribution as that of IgA. The presence of SC in the hepatocytes reflects either the synthesis of SC or the transport of pre-assembled SC-IgA by liver cells. The significance of transfer of IgA from serum into bile is as yet unknown. However, the transhepatic passage of IgA may represent a reinforcement of local intestinal immunity, as part of the gut-originated IgA antibodies, which fail to go through the intestinal mucosa, may still gain access to the lumen of the gut.