PRODUCTION OF MONOCLONAL-ANTIBODIES RECOGNIZING THE PEPTIDE CORE OF MUC2 INTESTINAL MUCIN

A peptide based on the tandem repeat sequence of MUC2 mucin was used t o produce a series of monoclonal antibodies (MAb). The fine specificit y of these antibodies and their implications for MUC2 expression are p resented. Three of the MAbs, 996/1, 996/7 and 995/25, were specific to the MUC2p and failed to bind to peptides based on the MUC1,3,4 tandem repeat sequences whereas three others, 994/152, 994/91 and 996/36, cr oss reacted with the MUC2p and the MUC3 tandem repeat peptide but not the MUC1 and MUC4 peptides. An antigen, affinity purified from a color ectal tumour on one of the MUC2p-specific MAbs, 996/1, was shown to be a high molecular weight polydisperse, mucin-like antigen. Two of the MAbs, 996/1 and 994/152, recognised MUC2 in tissue sections, although the fine specificity varied between the two MAbs, with 994/152 strongl y staining gastric, ileum and kidney epithelia, and MAb 996/1 intensel y staining colon, liver and prostate tissues. These antibodies also st ained a colorectal cell line, and MAb 994/152 also stained a gastric a nd an ovarian cell line. Six of the MAbs were used to stain colorectal tumour and adjacent 'normal' colonic mucosa sections. All six stained normal mucosa, but only two of the MAbs, 996/1 and 994/91, stained tu mour tissue. The staining probably reflects exposure of cryptic epitop es due to varying levels of glycosylation in different tissues. These anti-MUC2p MAbs may help in determining the normal role of MUC2 mucin and how it is subverted in malignancy.