Carcinoembryonic Antigen (CEA)

Accurate (C234, 12-140-10, MIC0101), Axcel/Accurate (A5B7, polyclonal), Biodesign (ME. 104, CEJ 065, MAM6, 9207, 9201, 9203, polyclonal), Biodesign/Immunotech Inc (CEJ065), Biogenesis (6.2, 1G9/9, 10, MAC601, polyclonal), Biogenex (SP-651, TF3H8-1), Biosource, Calbiochem, Caltag Laboratories (CEA6.2), Cymbus Bioscience (85A12), Dako (11-7, polyclonal), E-Y Labs, Fitzgerald (M94129, M94130, M94131, M94132, M 2103124, M2103125, polyclonal), Harlan Sera Lab/Accurate (601), Immunotech Inc (FJ95, CEJ 065), Immunotech SA (F023C5), Novocastra (85A12, 12-140-10), Oncogene (TF3H8), Shandon Lipshaw (CEJ065), Sigma Chemical (C6G9) and Zymed (ZCEA1, COL-1).

This antibody can be used on formalin-fixed, paraffin-embedded tissue sections. Prolonged fixation in buffered formalin may destroy the epitope. Antibody to CEA may also be used for frozen sections. Trypsinization is essential for antigen unmasking.

CEA consists of a heterogeneous family of related oncofetal glycoproteins (approximately 200 kD molecular weight) which is secreted into the glycocalyx surface of gastrointestinal cells. CEA was first described in 1965 as a specific antigen for adenocarcinoma of the colon and the digestive tract of a 2-6-month-old fetus. The monoclonal antibody to CEA was raised using tumor cells derived from a hepatic metastasis of colonic carcinoma (Rogers et al, 1976). CEA is a complex glycoprotein so even after purification, some degree of molecular heterogeneity exists (Sheibani et al, 1992). Therefore antibodies to CEA, particularly polyclonal, commonly react against a non-specific crossreactive antigen (NCA) located in normal colon and granulocytes. Because of the crossreactivity of most heterologous anti-CEA antisera with NCA, the results obtained when polyclonal anti-CEA antibody was used, have recently been questioned (Whitaker et al, 1982). The anti-NCA reactivity of anti-CEA antibody is demonstrated with positive immunoreaction in polymorphonuclear leukocytes and macrophages since the cells lack CEA antigen, but contain NCA. Therefore it is recommended that positive results obtained with a polyclonal anti-CEA antibody without preabsorption with NCA be interpreted as non-specific (Sheibani et al, 1992). Even monoclonal antibodies to CEA may crossreact with other molecules of the CEA family, including NCA (Sheibani et al, 1992). Therefore, each antibody needs to be evaluated to avoid non-specific results.

CEA is found in several adenocarcinomas, such as colon, lung, breast, stomach and pancreas. Some studies have found over 70% of adenocarcinomas from a variety of organs to be positive, with no evidence of expression of CEA by neoplastic cells in several hundred cases of malignant mesothelioma (Shebani et al, 1986, 1988). Hence, in these studies, expression of CEA by adenocarcinomas and their absence in mesothelioma represent valuable markers in the discrimination of mesotheliomas from morphologically similar adenocarcinomas involving any organ (Sheibani et al, 1992). However, it should be stressed that such results are dependent on the antibody evaluation in independent laboratories. Another study (Stirling et al, 1990) obtained cytoplasmic or membrane-related staining in five of 45 cases of mesothelioma studied. Occasional hyaluronaterich epithelial mesotheliomas may produce false positivity with CEA, although this staining can be abolished by hyaluronidase digestion prior to immunoprocessing (Robb 1989). A study examining multiple-marker immunohistochemical phenotypes to distinguish between malignant pleural mesothelioma from pulmonary adenocarcinoma, demonstrated CEA to be the best single marker (Brown et al, 1993): positive-97% specific and sensitive for adenocarcinoma; negative-97% specific and sensitive for mesothelioma (Appendix 1.16). Polyclonal CEA is also useful for the demonstration of bile canaliculi in hepatocytes and the cells of hepatocellular carcinoma in both cytologic preparations and tissue sections (Appendix 1.8). Although the presence of bile canaliculi is specific for hepatocytes, its sensitivity is low.

The fact that no single antibody is sufficiently specific and sensitive for the distinction of mesothelioma from adenocarcinoma necessitates the use of a panel of antibodies comprising a broad-spectrum cytokeratin, monoclonal CEA, Leu M1 and BER-EP4, which allows for confident differentiation of these tumors in approximately 90% of cases (Leong & Vermin-Roberts, 1994; Attanoos et al, 1996). Colonic carcinoma is the favored positive control tissue for antibodies against CEA.

•Attanoos RL, Goddard H, Gibbs AR 1996. Mesothelioma-binding antibodies: thrombomodulin, OV632 and HBME-1 and their use in the diagnosis of malignant mesothelioma. Histopathology 29: 209-215.

•Brown RW, Clark GM, Tandon AK, Allred DC 1993. Multiple-marker immunohistochemical phenotypes distinguishing malignant pleural mesothelioma from pulmonary adenocarcinoma. Human Pathology 24: 347-354.

•Leong AS-Y, Vermin-Roberts E 1994. The immunohistochemistry of malignant mesothelioma. Pathology Annual 29: 157-179.

•Robb JA 1989. Mesothelioma versus adenocarcinoma: false positive CEA and Leu-M1 staining due to hyaluronic acid (Letter). Human Pathology 20:400.

•Rogers GT, Searle F, Bagshawe KD 1976 Carcino embryogenic antigen: isolation of a subfraction with high specific activity. British Journal of Cancer 33:357-362.

•Sheibani K, Battifora H, Burke JJ 1986. Antigenic phenotype of malignant mesotheliomas and pulmonary adenocarcinomas. An immunohistologic analysis demonstrating the value of the Leu M1 antigen. American Journal of Pathology 123: 212-219.

•Sheibani K, Azumi N, Battifora H 1988. Further evidence demonstrating the value of Leu-M1 antigen in differential diagnosis of malignant mesothelioma and adenocarcinoma: An immunohistologic evaluation of 395 cases. Laboratory Investigation 58:84A.

•Sheibani K, Esteban JM, Bailey A, Battifora H, Weiss LM 1992. Immunopathologic and molecular studies as an aid to the diagnosis of malignant mesothelioma. Human Pathology 23:107-116.

•Stirling JW, Henderson DW, Spagnolo DV, et al 1990. Unusual granular reactivity for carcinoembryonic antigen in malignant mesothelioma. Human Pathology 21:678-679.

•Whitaker D, Sterrett GF, Shilkin KB 1982. Detection of tissue CEA-like substance as an aid in the differential diagnosis of malignant mesothelioma. Pathology 14: 255-258.

Manual of diagnostic antibodies for immunohistology / Anthony S.-Y. Leong, Kumarasen Cooper, F. Joel W.-M. Leong.