[Study on the local immune system of the human pancreas and liver--ultrastructural localization of IgA and secretory component].

The localization of IgA and secretory component (SC) in human pancreas and liver was studied by the peroxidase-labeled antibody method. Ultrastructurally, SC was found in perinuclear spaces, in endoplasmic reticulum, in saccules associated with Golgi complexes, on basolateral membranes, in endocytic invaginations and in cytoplasmic vesicles of the pancreatic epithelial cells and the biliary epithelial cells. IgA was found in subepithelial connective tissues, in basement membrane and on basolateral membranes, in endocytic invaginations and in cytoplasmic vesicles of the cells in which SC was visualized. From the above findings, we concluded that IgA was transported into pancreatic juice and bile by SC-mediated vesicular transport mechanism across the pancreatic epithelial cells and the biliary epithelial cells. The presence of local immune system in human pancreas and liver is assumed to be one of the principal factors that prevent severe infection after surgical operation for the organs.