Ultrastructural localization of c-erbB-2 gene product in transitional cell carcinoma of the urinary tract

The c-erbB-2 gene product was demonstrated immunoelectron microscopically in human transitional cell carcinomas of the urinary tract. Two antibodies specific for the c-erbB-2 gene product were used: a polyclonal antibody directed to the intracellular domain and a monoclonal antibody recognizing an epitope in the extracellular domain. The immunoreaction with the polyclonal antibody was observed on cell membranes and the cytoplasmic area beneath membranes with particularly strong reaction on microvilli. The immune reaction with the monoclonal antibody was confined to cell membranes with a linear pattern. Amorphous deposits in the intercellular spaces were also immunoreactive with the monoclonal antibody directed to an extracellular epitope, suggesting that a part of the c-erbB-2 gene product may be released from the cancer cell membranes into the extracellular space.