Simple mucin-type Tn and sialosyl-Tn carbohydrate antigens in salivary gland carcinomas

Abstract

Neoplastic transformation is associated frequently with changes in the glycosylation process. Simple mucin-type glycosylation in cancer cells has been found to be characterized by incomplete synthesis with precursor accumulation, leading to the exposure of the structures Tn and sialosyl-Tn, which are normally cryptic in human cells and secretions, including saliva and salivary glands. Paraffin sections from 50 salivary gland carcinomas of different histologic types were investigated with immunohistologic studies and a panel of monoclonal antibodies with well-defined specificity for Tn and sialosyl-Tn. Tn and sialosyl-Tn antigens were expressed in the cytoplasm of glandular differentiated cells; in the luminal membranes and mucinous content of the glandular differentiated areas in almost all mucoepidermoid carcinomas and adenocarcinomas; and in carcinoma in pleomorphic adenoma, when the malignant component was an adenocarcinoma. In contrast, acinic cell carcinomas and adenoid cystic carcinomas expressed only minimal amounts of Tn and sialosyl-Tn, and the staining was seen only in relation to the luminal membrane and mucin of a few glandular structures. Mucin-type Tn and sialosyl-Tn may be regarded as markers of a glandular differentiation pattern in salivary gland carcinomas. The cellular location of the antigen-antibody complex indicates that they are synthesized and secreted from the tumor cells into saliva or serum.