Double and triple immunocytochemical labelling at the light microscope level in histopathology

Double and triple immunocytochemical detection methods for routine use in histopathology were investigated. For double immunostaining, the combinations of immunogold-silver staining (IGSS, black) with an immunoperoxidase method (3-amino-9-ethylcarbazole, red-brown) or with an immunoalkaline phosphatase method (Fast Red TR, red) proved very useful. These were followed by a Haematoxylin counterstain. An alternative approach using immunoperoxidase (red-brown) and immunoalkaline phosphatase (Fast Blue, BB, blue) methods was also successful, particularly for frozen sections of unfixed tissue and for the establishment of intermediate filament coexpression in tumours. The coexistence of desmin with vimentin in rhabdomyosarcoma, and of glial fibrillary acidic protein with vimentin in ependymoma, could be demonstrated directly by means of non-crossreacting murine and rabbit antibodies in the above combinations. The black (IGSS), red-brown (immunoperoxidase) and blue (immunoalkaline phosphatase) colours gave excellent contrast in triple immunostaining. The side-by-side demonstration of helper and suppressor T lymphocytes during renal allograft rejection, of kappa and lambda light chains in B-immunoblastic lymphoma, and of T and B lymphocyte populations in non-Hodgkin's lymphomas provided immediate information on the topography and cellular organization of the tissues.