Interferon-gamma tempers the expression of carcinoembryonic antigen family molecules in human colon cells: a possible role in innate mucosal defence.

Four carcinoembryonic antigen-related cell adhesion molecule (CEACAM)s, i.e. CEA, CEACAM1, CEACAM6 and CEACAM7, are localized to the apical glycocalyx of normal colonic epithelium and have been suggested to play a role in innate immunity. The expression of these molecules in colon carcinoma cells was studied at the mRNA and protein levels after treatment with interferon-gamma (IFN-gamma), interleukin-1beta, live bacteria or lipopolysaccharide. The colon carcinoma cell lines LS174T and HT-29 were studied in detail using real-time quantitative reverse transcriptase-polymerase chain reaction, immunoflow cytometry and immunoelectron microscopy. IFN-gamma, but not the other agents, modified expression of CEA, CEACAM1 and CEACAM6. None of the agents upregulated CEACAM7 expression. Two expression patterns were seen. HT-29 cells, which initially showed low quantities of mRNAs and proteins, displayed marked upregulation of both mRNAs and proteins. LS174T cells transcribed stable high levels of mRNA before and after treatment. Additionally, IFN-gamma induced increased cell surface expression of CEA, CEACAM1 and CECAM6. IFN-gamma has two important effects on the expression levels of the CEA family molecules in colon epithelial cells: direct upregulation of CEACAM1 and promotion of cell differentiation resulting in increased expression of CEA and CEACAM6 and decreased expression of CEACAM7.

Carcinoembryonic antigen gene family members in submandibular salivary gland: demonstration of pregnancy-specific glycoproteins by cDNA cloning.

We have recently shown that human submandibular salivary gland and saliva contain a number of glycoproteins belonging to the carcinoembryonic antigen (CEA) gene family. The members of the CEA family can be divided into the CEA subgroup and the pregnancy specific beta 1 glycoprotein (PSG) subgroup. The latter glycoproteins are abundant in placenta and fetal liver. Here we report that PSG's are expressed in normal adult submandibular salivary gland. Thus, cDNA cloning and sequencing gave two clones (SG5 and SG9) which coded for glycoproteins with a domain arrangement of N-A1-A2-B2-C and a third clone (SG8) which coded for a glycoprotein with a domain arrangement of N-A1-B2-C. SG5 is identical to PSG3, and SG9 to PSG1d, while SG8 most probably corresponds to PSG2. The 3' untranslated regions of the different members of the PSG subgroup contain highly homologous segments, suggesting a common evolutionary origin.

Tumor specificity of monoclonal antibodies to carcinoembryonic antigen. Immunohistochemical analysis.

The tumor specificity of twelve different monoclonal antibodies (Mabs) against carcinoembryonic antigen (CEA) was assessed by immunohistochemistry. The Mabs had previously been classified into three specificity groups (I-III) on the basis of their reactivity with purified CEA-related antigens by ELISA. Mabs belonging to specificity group III (n = 4) did not cross-react with any CEA-related antigen, including normal cross-reactive antigen of 160 kD molecular weight (NCA-160 = meconium antigen). All Mabs, except one, gave positive immunohistochemical staining of 75-100% of individual tissue samples of colorectal carcinomas and gastric adenocarcinomas. However, when tested against different normal adult tissues, the Mabs displayed marked differences in reactivity. Group III Mabs stained normal colon epithelium, but not parenchymal cells in other organs or, with one exception, cells belonging to the granulocyte and/or macrophage series. Group I and II Mabs, in contrast, stained parenchymal cells in normal colon, submandibular salivary gland, placenta, and pancreas (group I Mab only). They also stained infiltrating and circulating granulocytes and/or macrophages. Lack of cross-reactivity with NCA-160 is the single-best criterion for selecting anti-CEA Mabs with a high degree of tumor specificity. To ensure tumor specificity, CEA-positive, NCA-160-negative Mabs should be checked by immunohistochemistry against cryostat sections of colorectal carcinoma, normal pancreas, submandibular salivary gland, spleen, and liver and for reactivity against circulating granulocytes.

Epitope specificity and cross-reactivity pattern of a large series of monoclonal antibodies to carcinoembryonic antigen.

Monoclonal antibodies (MAbs) were produced against purified carcinoembryonic antigen (CEA) from liver metastases of colo-rectal and lung adenocarcinoma. Three and eight anti-CEA MAbs from the two groups were analyzed in detail. All antibodies were IgG1. With one exception they recognized epitopes present on all eight individual CEA preparations investigated irrespective of whether they were from colo-rectal or lung carcinoma. The exceptional MAb reacted with an epitope present on most but not all CEA preparations. With two, or possibly three, exceptions the MAbs recognized conformation dependent epitopes in the peptide moiety of CEA. One MAb reacted strongly with reduced and carboxymethylated CEA but only weakly with native CEA. Four MAbs appeared to be CEA-specific in that they did not react with any of the known CEA-cross-reactive substances including nonspecific cross-reactive antigen of 160,000 mol. wt (NCA-160). A total of nine different epitopes were detected in native CEA using this and our previous series [Hedin A., Hammarström S. and Larsson A. (1982) Molec. Immun. 19, 1641] of anti-CEA MAbs. With one exception practically all molecules (70-90%) in purified CEA preparations contained these epitopes.