DISTRIBUTION OF TN ANTIGEN RECOGNIZED BY AN ANTI-TN MONOCLONAL-ANTIBODY (MLS128) IN NORMAL AND MALIGNANT-TISSUES OF THE DIGESTIVE-TRACT

Alterations in the normal glycosylation process are often associated w ith oncogenic transformation. Using an anti-Tn monoclonal antibody, ML S128, we have investigated the immunohistochemical localization of Tn antigen in normal and malignant tissues of the digestive tract. In nor mal tissues, MLS128 was immunoreactive with the squamous epithelium of the esophagus and was weakly reactive with the columnar epithelia of the stomach, duodenum, colon, bile duct and pancreatic duct. In malign ant tissues, positive immunostaining was detected with high frequency (75%-100%) in carcinomas of the esophagus, stomach colon, biliary trac t and pancreas, whereas 2 of 11 (18%) hepatocellular carcinomas were p ositive. Tn antigen was detected in the upper two-thirds of the normal squamous epithelium, and was often detected in squamous cell carcinom as with cancer pearls (keratinization). These results suggest that the expression of Tn antigen is related to the differentiation of squamou s epithelium, or to keratinization. In normal columnar epithelial cell s, Tn antigen was localized mainly to the Golgi area. This intracellul ar localization was preserved in well-differentiated papillary adenoca rcinomas of the colon, but was lost in most cases of tubular adenocarc inomas.