Localization and serum concentration of secretory component during massive necrosis of human liver.

The serum concentration of secretory component was monitored in 9 patients with massive liver necrosis. During acute cytolysis, no increase in serum secretory component levels was observed. Later on, patients with fulminant evolution displayed minor elevations. Values as high as those usually found in acute hepatitis were only observed in cases with delayed liver failure. In these patients, levels were elevated before failure, dropped as liver failure developed, and rose again during recovery. This evolution of serum secretory component level cannot be accounted for by a defective liver clearance of circulating secretory component. It rather suggests a release into the blood of secretory component produced in the liver by cells other than damaged hepatocytes, possibly during liver regeneration. In 3 cases, secretory component localization in the liver was demonstrated by immunocytochemistry and was compared with that in normal liver and in obstructive jaundice. In normal liver, it was restricted to portal bile duct cells and lumens. In obstructive jaundice, additional secretory component staining was found in bile canaliculi. After fatal liver necrosis, secretory component was localized to portal ducts and to a variable proportion of the cholangiocytelike cells belonging to the numerous extraportal proliferating ducts. In these structures, 0.1%, 21%, and 4% of the cells were stained 3, 8, and 30 days after maximal cytolysis, respectively. Remaining hepatocytes and bile canaliculi or bile plugs were unstained. Therefore, portal cholangiocytes and extraportal cholangiocytelike cells are probably essential sources of secretory component in human liver. We propose that proliferation of extraportal cholangiocytelike cells, expression of secretory component synthesis by these cells, and their inability to secrete secretory component in a disorganized biliary tree result in the elevated serum concentration of secretory component observed after acute liver necrosis.