Identification of a colon-specific antigen (CSA) in normal and neoplastic tissues

An antigen has been isolated from a human signet-ring cell carcinoma serially growing in hamsters, GW-39, by saline, PCA, or phenol extraction, and has been found immunologically identical to a similarly extracted substance in normal human or hamster colon. No other hamster or human tissues or cells were found to contain this antigen, for which reason we have termed it colon-specific antigen, or CSA. CSA has been found to be distinct from the major blood group-specific antigens and from othercolon tumor-associated antigens, such as CEA, CCA-II, and CCA-III. It thus seems that a colon organ-specific antigen can be synthesized by this particular human tumor system. Hamsters immunized with CSA could reject cheek pouch grafts of GW-39 tumors, and tumor rejection by these animals correlated with their anti-CSA antibody titers. Preliminary characterization of CSA suggested that it is a glycoprotein on the cell surface having a molecular size of 30,000 to 50,000 daltons. It is proposed that CSA may play a role in the diagnosis of mucin-producing adenocarcinoma of the colon and in ulcerative colitis.