Comparison between conjugate and non-conjugate immunoperoxidase procedures with special reference to intracellular penetration. Application to albumin localization in rat hepatocytes.

Three immunoenzymatic methods, peroxidase-labelled antibody, peroxidase-labelled immunoglobulin Fab fragment and unlabelled antibody peroxidase-antiperoxidase methods were compared for albumin localization in rat hepatocytes. On liver cryostat sections observed with light microscopy, the peroxidase-antiperoxidase method was the most sensitive, since albumin was detectable at high dilutions of the primary layer antiserum. Penetration of the conjugated and non-conjugated antibodies into liver tissue was evaluated by electron microscope examination of ultrathin transverse sections cut from cryostat sections. The best penetration and staining of hepatocellular organelles were obtained with peroxidase-labelled Fab fragments.