Immunoperoxidase localization of colonic mucoprotein antigen in neoplastic tissues

The distribution of colonic mucoprotein antigen in various types of cancer was examined to determine whether the antigen might have a role as a tissue marker. An antiserum prepared against normal colon-derived colonic mucoprotein antigen and appropriately absorbed with mucinous ovarian cystadenocarcinoma fluid had reactivity limited to the colon and cecum when tested by immunoperoxidase against various normal adult tissue specimens. Among colon carcinomas, 60% of the tumors were stained, and a correlation with tumor differentiation was noted: seven of seven tumors were well differentiated; 21 of 35 tumors were moderately differentiated; and one of seven poorly differentiated tumors expressed the determinants. Of note was the absence of staining with gastric, pancreatic, lung, and endometrial mucin-producing carcinomas. Only one of five mucinous ovarian cystadenocarcinomas was positive for colonic mucoprotein antigen. The potential role of the mucin as a marker for colon carcinoma is discussed.