spective of its carrier (A78-G/A7, peanut agglutinin). To evaluate the coexpression of different epitopes by the same antigen, sandwich enzyme-linked immunoadsor-1 Institute of Pathology, University of Cologne, bent assays were performed. Cologne, Germany. RESULTS. Although MUC1 peptide antigen and MUC1-bound TF antigen were notdetectable in normal or transitional mucosa surrounding colorectal neoplasms, logne, Cologne, Germany. expression of these antigens in adenomas accompanied the development of high grade dysplasia. By contrast, MUC2 expression detected by the MoAb 4F1 was correlated with the progression of the adenoma-carcinoma sequence. In Cologne, Germany. well-and moderately differentiated colorectal carcinomas, the neo-expressed TF 4 Max-Delbrueck-Center of Molecular Biology, antigen is predominantly bound to MUC1. This feature could be demonstrated by 13125 Berlin-Buch, Germany. antigen coexpression using peptide and the TF antigen specific MoAbs. However, 5 Department of Obstetrics and Gynaecology, in mucinous carcinomas exhibiting a weak MUC1 peptide expression in most Royal Brisbane Hospital, Herston, Queensland, specimens, the presence of TF antigen on the MUC2 peptide core cannot be ruled Australia. out. CONCLUSIONS. TF antigen is strongly coexpressed with MUC1 mucin peptide core in the colorectal adenoma-carcinoma sequence, resulting in well-and moderately differentiated carcinomas. Only in mucinous carcinomas may it be coexpressed with MUC2 antigen.

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