Organ and tumor specificity of colon mucoprotein antigen in a rat model.

We purified a high-molecular-weight colon mucoprotein antigen (CMA) from normal F344 rat colon and from a transplantable dimethylhydrazine-induced colon carcinoma. Chemical analysis of the mucins showed similar amino acid and carbohydrate compositions. This finding was in contrast to the major differences that occurred in the composition of human CMA as a consequence of neoplasia. Immunohistochemical techniques were used in an examination of organ and tumor specificities. A New Zealand White rabbit antiserum against purified normal rat CMA, appropriately absorbed, detected a normal colon-specific determinant(s). The organ-specific determinant was lost as a consequence of neoplasia. However, a new tumor-specific determinant was then detected. CMA may have a potential role as an organ-specific marker of the neoplastic process.