Analysis of the carbohydrate specificity of ISOBM TD-4 Workshop anti-MUC1 antibodies.

The panel of ISOBM TD-4 Workshop antibodies was tested against a range of carbohydrate antigens consisting of (a) ovarian cyst mucins expressing A, B, H, Le(a), Le(x), Le(b), Le(y) and precursor (nonfucosylated) specificities, (b) ovine submaxillary mucin (OSM, expressing sialyl Tn) and desialylated OSM (expressing Tn) and (c) synthetic glycoconjugates (Le(a)-PAA and Le(x)-PAA). The assay used was an ELISA method using rabbit anti-mouse Ig as the second reagent. Thirty-five of the 51 antibodies were unreactive with this group of antigens and presumably react with MUC1 peptide or a carbohydrate specificity not represented. Two MAbs (127 and 128) detected Le(x) antigen and one MAb (157) reacted with A blood group. MAb 151 (and possibly 152) detected sialyl Tn epitopes. Three antibodies (139, 149 and 168) reacted with nonfucosylated structures (possibly LNT or LNneoT). A number of MAbs (137, 145, 162, 163 and 164) reacted widely with the panel of antigens; whether these are nonspecific reactions due to 'sticky' antibodies or caused by the presence of MUC1 peptide in the antigen preparations is uncertain.