Peroxidase-labeled antibody staining for carcinoembryonic antigen of cytologic specimens for light and electron microscopy.

Immunohistochemical staining methods suitable for light and electron microscopic examination of cytologic specimens are described. Application of the methods clearly demonstrated the localization of carcinoembryonic antigen (CEA) in adenocarcinoma cells in body fluids. The use of a peroxidase-labeled antibody method permits rapid penetration of the cells by the antibody, which is not achieved by the peroxidase-antiperoxidase or avidin-biotin-peroxidase-complex staining methods. Since mesothelial and inflammatory cells are negative for CEA, the staining of body fluids for CEA is expected to be an extremely useful tool for the differential diagnosis of adenocarcinoma.