Immunohistochemical distribution of S-100 protein and glial fibrillary acidic protein in normal and neoplastic salivary glands.

Immunohistochemical localization of S-100 protein, its alpha and beta subunits, and glial fibrillary acidic protein (GFAP) in normal and neoplastic salivary glands was studied by the peroxidase-antiperoxidase method and immunoblot analysis. Positive immunostaining for S-100 protein was observed in pleomorphic adenoma, adenolymphoma, tubular adenoma, adenoid cystic carcinoma, acinic cell tumour, adenocarcinoma and carcinoma in pleomorphic adenoma. S-100 protein was localized in myoepithelial cells, epithelial cells of intercalated ducts and serous acinar cells of normal salivary gland. Both alpha and beta subunits of S-100 protein showed almost identical distribution in normal and neoplastic salivary glands, but skeletal muscle cells were alpha-positive/beta-negative whereas Schwann cells and fat cells were alpha-negative/beta-positive in the stroma and neighbouring tissue. GFAP was only found in pleomorphic adenoma and its malignant counterpart. Immunoblot analysis showed that the GFAP-related antigen consisted of several polypeptide bands with a molecular weight ranging between 35,000 to 50,000 daltons.