Monoclonal antibody CIBCHTB1 defining an epitope on carcinoembryonic antigen (CEA)

Carcinoembryonic antigen (CEA) is an oncofoetal protein first identified by Gold and Freedman (1965) in colorectal cancer. It is a cell surface tumor marker which has been characterised as a heterogenous group of glycoproteins. It is also present in a variety of benign and non-neoplastic diseases like ulcerative colitis, Adenomatous polyp, Liver cirrhosis and other cancers like GI tract tumors, Cancer of the breast, lung, ovary, pancreas, prostate, hepatoma etc. Elevated CEA levels serve as clinical tool in the diagnosis, monitoring, detecting early any recurrence or metastasis and in prognostication for confirmed colorectal cancers. In order to develop an Enzyme Immuno Assay and immunocytochemical assay for CEA, an MAb designated as CIBCHTB1 has been generated using CEA isolated from a cell line HT115, human adenocarcinoma of the colon, as immunogen by the conventional Hybridoma technology. This MAb of IgG1 isotope was selected by screening of culture supernatents by ELISA and then by its high binding affinity with HT115 cells as revealed by flowcytometric analysis. By ABC method of immunocytochemical assay, this Ab exhibited strong staining of cells in frozen tissue sections of normal colon and malignant colorectal lesions and various other types of human cancers. This MAb has useful application to study the expression of CEA in human cancers. Serum CEA levels of patients with colorectal cancers and other CEA producing cancers and controls determined by EIA using this MAb were in good correlation with the results obtained using commercial kit. The diagnostic potential of this Mab in the management of colorectal cancers is discussed.