Monoclonal antibody recognizing a core epitope on mucin

Monoclonal antibody TH1 (IgM) was prepared by immunizing mice with deglycos ylated (TFMSA-treated) cystic fibrosis mucin. TH1 reacted strongly with TFM SA treated cystic fibrosis mucin but not with the fully glycosylated mucin, indicating reactivity with a core mucin epitope. TH1 showed no reactivity with ovine mucin (98% of glycans as sialyl-Tn) but reacted strongly with de sialylated ovine mucin, indicating the epitope for this mab was the Tn-anti gen (O-linked GalNAc). However, TH1 showed no reactivity with Tn-positive r ed brood cells, and the binding of TH1 was not inhibited by GalNAc at 2.5 m g/ml, illustrating the importance of the peptide sequence to which the GalN Ac is attached. TH1 stained the majority of cancers of the colon, lung, sto mach, ovary, breast, and cervix, and the cellular distribution of this anti gen in normal tissue suggested reactivity with immature mucin. This antibod y appears to be a useful reagent for the detection of immature mucin.