Localization of S-100 protein and glial fibrillary acidic protein-related antigen in pleomorphic adenoma of the salivary glands.

Pleomorphic adenoma of the salivary glands was studied by the peroxidase-antiperoxidase method and Ouchterlony's double diffusion for the presence of so-called nervous system-specific proteins, S-100 protein, glial fibrillary acidic protein (GFAP), and astroprotein. Positive immunostaining for S-100 protein was observed in tumor cells of epithelial, myxomatous, and chondroid areas. An immunodiffusion test confirmed its presence in the tumor. Normal salivary glands were also stained with anti-S-100 serum, but the reaction was less intense than that of tumor. Specific immunostaining for GFAP and astroprotein was found in a small number of cells of myxomatous and chondroid areas and occasionally in cells in epithelial areas. An immunodiffusion test suggests that the GFAP-related antigen of the pleomorphic adenoma showing a minor heterogeneity of antigenic determinants is almost identical with GFAP. Normal salivary glands did not stain with GFAP or astroprotein antisera, nor did they react with anti-GFAP serum by immunodiffusion. Thus, the S-100 protein and GFAP-related antigen may be actively synthesized in adenoma cells during the course of tumor development. In addition, the GFAP-related antigen is considered to be a tumor-associated antigen of pleomorphic adenoma of the salivary glands.