Immunoperoxidase labelling of previously stained tissue sections: application in oral histopathology.

We have investigated by the avidin-biotin peroxidase technique a wide variety of recognized cellular antigens in paraffin sections of both normal and pathological material which have been previously stained with hematoxylin and eosin. The intensity of peroxidase reaction was adequate to permit the diagnosis and the background of the immunoreaction minimal. This technique therefore, appears useful either for retrospective analysis of cellular antigens or when limited unstained material is available.