Antitumor monoclonal antibodies generated by immunization with mucins

This report describes the development and characterization of monoclonal antibody EG2.3. Although produced from a fusion that used splenocytes from donor mice immune to bovine salivary mucin (BSM), EG2.3 bound selectively to a number of human tumor cell lines including colon adenocarcinoma LS174T. Therefore, EG2.3 was compared to B72.3, another mucin (TAG-72) binding monoclonal antibody that also binds to LS174T. Like B72.3, EG2.3 reacted with an epitope on TAG-72. However, these two MAbs differed in a number of ways. Treatment of mucin or TAG-72 with periodate did not reduce the binding of EG2.3 to either antigen. In contrast, B72.3 did not react with either periodate treated antigens. Removal of sialic acid from either BSM or TAG-72 compromised the reactivity of both EG2.3 and B72.3. It was concluded that the EG2.3 binding site was distinct from the carbohydrate structure detected by B72.3.