RESUMO
The Thomsen-Friedenreich antigen (T) is the core disaccharide of O-glycosylated complex carbohydrates and is presumed to be a cancer-associated carbohydrate antigen. However, we recently found that the expression of alpha-T and alpha 1-2 fucosyl alpha-T in the gastric surface epithelia was regulated allogeneically. In the present study we addressed their changes in gastric differentiation disorders. Expression of the T-related antigens was studied histochemically with monoclonal antibody MBrl and peanut agglutinin in 22 normal, 14 metaplastic, and 54 cancerous tissues. The sialylated antigens were detected after neuraminidase digestion. Gastric mucins were purified and examined to determine whether they were the carrier molecules of T. Expression of the normal antigens was decreased or not detected in about 80% of both disorders. Neosialylation of the T-related antigens was observed in the goblet cells of all metaplastic tissues. The absorptive cells did not express any T-related antigens. In gastric cancers, blocked synthesis, i.e., precursor accumulation or totally negative expression, was observed in approximately 66% and neosialylation in approximately 40%. The T-related antigens were carried by mucins. We conclude that blocked synthesis of the T-related antigens was found in a cancer-specific manner. Neosialylation was invariably associated with intestinal metaplasia and occasionally with cancer.