A random arrangement of albumin-containing hepatocytes seen with histo-immunologic methods. I. Verification of the artifact.

The cellular and subcellular localization of albumin in hepatocytes of adult male rats was established with immunofluorescence and immunoperoxidase techniques. Livers were fixed while either filled or devoid of blood. In some rats, prior treatment with cycloheximide was used to deplete the albumin content of hepatocytes. Immunofluorescence of blood-free livers from untreated rats showed that all hepatocytes contained albumin. However, using the peroxidase method, the amount of immunoprecipitate in cisternae of the rough endoplasmic reticulum was so slight that specific localization of albumin was impossible. Yet in all cases, a positive reaction for the presence of albumin was seen on ribosomes attached to the endoplasmic reticulum. In contrast, immunofluorescence of blood-filled livers from untreated rats and those previously injected with cycloheximide showed that only a few scattered hepatocytes were positive for albumin. In these cases, subcellular localization of albumin was obvious because the immunoprecipitate was found in heavy concentration, buy only in the cytosol compartment.