Immunocytochemical demonstration of filamentous structures in the parotid gland. Occurrence of keratin and actin in normal and tumoral parotid gland with special respect to the myoepithelial cells.

The aim of this study was to analyze the filament distribution in the parotid gland and their tumors. A correlation to the histogenetic implications and histological properties was attempted. Normal rat and human parotid glands as well as pleomorphic adenomas and squamous cell carcinomas of this gland were examined by the indirect immunoperoxidase technique using antibodies to the keratin polypeptide of 67,000 dalton, and 55,000 dalton and anti-actin auto-antibodies. Both keratin and actin antigens were demonstrated in the duct system and in the myoepithelial cells of the normal salivary glands. The acinar cells remained negative. In pleomorphic adenomas, there were numerous keratin-positive spindle-shaped cells which represented the so-called myoepithelial cells. These cells were demonstrated to contain actin, too. The tubular duct-like structures were labeled by keratin antiserum and by anti-actin auto-antibodies. In squamous cell carcinomas, the majority of the tumor cells were strongly labeled by keratin antibodies. Actin was detected in these malignant cells, too. Our results show important differences in the cellular elements of the normal salivary glands with regard to their filament distribution. In normal and tumoral conditions, our findings support the hypothesis of the epithelial nature of the myoepithelial cells. Our preliminary results encourage the research of filamentous structures for scientific and diagnostic purposes.