Monoclonal antibodies against CEA-related components discriminate between pancreatic duct type carcinomas and nonneoplastic duct lesions as well as nonduct type neoplasias.

The expression of CEA and related antigens in formalin-fixed paraffin-embedded tissues of normal pancreas and different pancreatic neoplasms was studied immunocytochemically using three monoclonal antibodies (MAbs) recognizing different epitopes on CEA and related antigens. Additionally, a number of extrapancreatic malignancies were tested. The epitope recognized by MAb 250 (present on CEA and NCA 95) was expressed in all but one pancreatic ductal adenocarcinoma and ampullary carcinoma (42/43). The MAb 431 defined epitope (present only on CEA) was less frequently found (27/43). MAb 374, defining an epitope on CEA, NCA 95 and NCA 55 proved to be nearly as sensitive as MAb 250, but also reacted with normal duct epithelium. In contrast, MAb 250 and MAb 431 discriminated clearly between reactive duct lesions and malignant duct changes. Moreover, these MAbs differentiated between pancreatic duct carcinomas and nonduct type carcinomas as well as benign pancreatic tumours. In duct type carcinomas, the strongest staining was observed in well differentiated tumours. No discrimination was possible between pancreatic carcinomas and other adenocarcinomas of the gastrointestinal tract nor between most of the lung carcinomas and some other malignancies, specified below. MAb 250 and MAb 431 failed to react with hepatocellular carcinomas, renal cell carcinomas, carcinoids, sarcomas and melanomas. The findings suggest that paraffin-embedded tissues of pancreatic duct type carcinomas, in contrast to nonduct type tumours and normal ducts, are distinguished by the presence of a CEA and NCA 95 related epitope.