Immunohistochemical localization of human liver specific protein using rabbit antisera and the avidin-biotin complex technique.

A sensitive enzymatic avidin-biotin complex technique was utilized to locate the antigenic sites in human liver which react with rabbit antibodies to human liver specific protein (LSP). Depending on the rabbit antiserum used, anti-LSP reactive material was seen in different locations. (1) diffusely distributed in liver parenchymal cells, (2) in both hepatocyte cytoplasm and plasma membrane and (3) in hepatocyte plasma membrane only. The cytoplasmic staining was partially or totally abolished by preabsorption with human kidney homogenate whilst the plasma membrane staining remained uninfluenced. The latter was apparently confined to bile canalicular walls and may be liver specific in contrast to the cytoplasmic reaction which seems to be due to antigen determinants cross-reacting with tissue components in kidney.