Expression of S-100 protein and glial fibrillary acidic protein in cultured submandibular gland epithelial cells and salivary gland tissues. Histogenetic implication for salivary gland tumors.

S-100 protein and glial fibrillary acidic protein (GFAP) were studied in human salivary gland tissues and human cultured submandibular gland epithelial cells. Immunohistochemically, ductal cells in normal salivary gland tissues were positive for S-100 protein and GFAP, but myoepithelial cells were uniformly negative. Immunocytochemically, cultured submandibular gland ductal cells were positive for S-100 protein and GFAP. By immunoblotting analysis of the cultured cell lysates, a 6.5-kd S-100 protein was detected. This band corresponded to S-100 protein purified from bovine brain. The cultured submandibular gland cells expressed 49- and 54-kd GFAP polypeptides. These results have important implications for the histogenesis of salivary gland tumors.