HUMAN EPITHELIAL RELATED ANTIGEN (HERA) IN SALIVARY-GLANDS AND THEIR TUMORS - IMMUNOHISTOCHEMICAL OBSERVATIONS

The expression of human epithelial related antigen(hERA), a 40 kD tran smembrane glycoprotein assigned to one of the small cell lung cancer a ntigen was evaluated in normal salivary glands and their tumors using immunohistochemical methods. In normal salivary gland acini, hERA was seen in lateral borders and basal plasma membrane of serous cells of t he parotid and submandibular glands and in the basal layer of mucous c ells of the sublingual and minor oral glands, the luminally projecting cell membrane being consistently unreactive. In ductal segments, hERA was seen in basal infoldings and lateral borders of striated duct cel ls, excretory ducts or interlobular ducts and the ductal basal cells i n particular, were devoid of hERA immunostaining. Salivary pleomorphic adenoma showed luminal borders of tubulo-ductal structures immunoreac tive for hERA whereas the non-luminal or the neoplastic myoepithelial cells were consistently unreactive. A similar pattern of immunoreactiv ity was observed in Warthin's tumor where lateral borders of luminally located tall columnar tumor cells showed reaction products whereas th e basal cells were unreactive. Mucoepidermoid carcinoma showed hERA in epidermoid and intermediate tumor cells, but not in mucous secreting cells. In adenoid cystic carcinoma reaction product for hERA was seen in a limited number of lumen-lining cells and again the non-luminally located neoplastic myoepithelial cells were unreactive. The results of the present study suggest that hERA may be a useful marker to detect luminal cell components in salivary tumor and, apart from the neoplast ic myoepithelial cells or their counterparts, these luminally located cells may have a potential implication in salivary gland tumorigenesis .