TRANSPORT BY HEPATOCYTES OF IMMUNOGLOBULIN-A FROM BLOOD TO BILE VISUALIZED BY AUTO-RADIOGRAPHY AND ELECTRON-MICROSCOPY

Abstract

Polymeric myeloma Ig[immunoglobulin]A labeled with 125I, was injected i.v. into rats killed 5, 30 or 60 min later, and the livers were removed, fixed and sectioned. Autoradiographs of ultra-thin sections examined in the EM showed that the IgA 1st became bound to the plasma membrane of the hepatocytes, but after 30 min much of it was transported across the cytoplasm and was localized around the bile canaliculi. Autoradiographs of 1 .mu.m sections examined in the light microscope showed the contents of the bile ducts in the portal tracts to be labeled heavily. Rapid transport of IgA across the liver was confirmed and the hepatocytes are apparently the cells that carry it out. No intracellular organelle or vesicular structure, discernible within the resolving power of the techniques used, was implicated in the transport mechanism.