Abstract
Trichosanthesjaponica agglutinin I (TJA-I) having a high affinity to the NeuAcα2-6Galβ1-4GIcNAc terminal sequence was used for an immunohistochemical study to analyze the expression of the NeuAcα2-6Gal structure in human colonic tissues. A TJA-I binding substance was detected in the mucosa of colonic carcinoma, but not in the normal and transitional mucosa. The TJA-I staining was correlated with the degree of histo logical differentiation of the carcinoma. TJA-I preferentially stained well-differentiated and moderately differentiated adenocarcinoma. In the carcinoma containing mucin lakes, the TJA-I staining reaction was either weak in intensity or negative. A comparative study using monoclonal antibody against sialosyl-Tn antigen (NeuAcα2-6-GaINAc) known to be expressed in colonic carcinoma tissues revealed that the areas exhibiting strong expressions of siaosyl-Tn antigen separated from the areas vividly reactive for the TJA-I staining. In addition, the expression of sialosyl-Tn antigen, unlike the TJA-I staining, was strong in the mucinous areas of the carcinoma. The results obtained in the present study suggest the possibility that a comparative staining method with TJA-I and monoclonal antibody against sialosyl-Tn antigen could be helpful to the diagnosis of human colonic carcinoma.
