Separation of distinct MUC2 mucin glycoforms using two anti-peptide monoclonal antibodies.

Two monoclonal antibodies (MAb996 and MAb994) were produced by immunisation with a synthetic peptide with a sequence based upon that of the protein co re of the gastrointestinal MUC2 mucin. The epitopes were identified as T G T Q for MAb996 and P T G T Q for MAb994. Antibody competition tests also co nfirmed the overlapping nature of the epitopes for the two antibodies. MAb9 94 and MAb996 were employed in immunoadsorbent columns for the fractionatio n of human colorectal carcinoma tissue extracts. While the two antibodies d isplayed only relatively minor differences in immunological specificity and affinity for the immunising synthetic MUC2 mucin core related peptide, the y had the capacity to separate antigenically distinct molecules when used a s immunoadsorbents. The findings indicated that subfractions of MUC2 antibo dy-defined mucins exist in human carcinomas and that these may be distingui shed by the differential exposure of determinants in the mucin protein core . The results are in accord with the view that aberrant patterns of glycosy lation of mucins in human intestinal tumours produces a spectrum of variabl y glycosylated macromolecules.