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 core 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 confirmed the overlapping nature of the epitopes for the two antibodies. MAb994 and MAb996 were employed in immunoadsorbent columns for the fractionation of human colorectal carcinoma tissue extracts. While the two antibodies displayed only relatively minor differences in immunological specificity and affinity for the immunising synthetic MUC2 mucin core related peptide, they had the capacity to separate antigenically distinct molecules when used as immunoadsorbents. The findings indicated that subfractions of MUC2 antibody-defined mucins exist in human carcinomas and that these may be distinguished by the differential exposure of determinants in the mucin protein core. The results are in accord with the view that aberrant patterns of glycosylation of mucins in human intestinal tumours produces a spectrum of variably glycosylated macromolecules.