Abstract
Six immunoglobulin G monoclonal antibodies reactive with carcinoembryonic antigen (CEA) were evaluated with respect to parameters implicated in their potential diagnostic application and use as tumor targeting agents for cytotoxic drugs or plant or bacterial toxins. Antibody reactivity with surface antigens of the MKN-45 gastric tumor cell line was demonstrated by flow cytofluorimetry. In a subcellular membrane binding assay, each antibody reacted preferentially with membranes isolated from colorectal tumor tissue in comparison with their reaction with membranes from adjacent, apparently normal colonic mucosa. Three of the antibodies (NCRC-23, C228, and 11.285.14) reacted specifically with CEA with little or no reaction with the cross-reacting antigen, NCA. The remaining three antibodies (C24, C161, and C198) were reactive with both CEA and NCA. Analysis of the epitopes defined by these antibodies was performed by competitive binding inhibition assays evaluating the capacity of unlabeled antibodies to compete with 125I-labeled antibodies in their binding to CEA. In addition, double determinant or ‘sandwich’ radioimmunoassays were employed to examine the coexpression of epitopes on CEA molecules. These studies permitted an epitope map to be constructed which describes the coincidence, overlapping, or independent expression of both CEA specific epitopes and epitopes shared between CEA and NCA. The map may be employed for the selection of antibodies for diagnostic and therapeutic use.
Keywords: Carcinoembryonic Antigen, Membrane Binding, Bacterial Toxin, Normal Colonic Mucosa, Unlabeled Antibody
References
- 1.Baldwin RW. Monoclonal antibody targeting of anticancer agents: Mühlbock Memorial Lecture. Eur J Cancer Clin Oncol. 1985;11:1281. doi: 10.1016/0277-5379(85)90304-9. [DOI] [PubMed] [Google Scholar]
- 2.Begent RHJ. Recent advances in tumor imaging: Use of radiolabelled anti-tumor antibodies. Biochim Biophys Acta. 1985;780:151. doi: 10.1016/0304-419x(84)90003-9. [DOI] [PubMed] [Google Scholar]
- 3.Blaszczyk M, Pak KY, Herlyn M, Lindgren J, Pessano S, Steplewski Z, Koprowski H. Characterization of gastroin-testinal tumor-associated carcinoembryonic antigen-related antigens defined by monoclonal antibodies. Cancer Res. 1984;44:245. [PubMed] [Google Scholar]
- 4.Corvalan JRF, Axton CA, Brandon DR, Smith W, Woodhouse C. Classification of anti-CEA monoclonal antibodies. In: Peeters H, editor. Protides of the biological fluids, vol 31. Oxford: Pergamon Press; 1984. pp. 921–924. [Google Scholar]
- 5.Dillman RO, Beauegard JC, Sobol RE, Royston I, Bartholomew RM, Hagan PS, Halpern SE. Lack of radiommunodetection and complications associated with monoclonal anticarcinoembryonic antigen antibody cross-reactivity with an antigen on circulating cells. Cancer Res. 1984;44:2213. [PubMed] [Google Scholar]
- 6.Durrant LG, Robins RA, Armitage NC, Baldwin RW, Hardcastle JD. Association of antigen expression and DNA ploidy in colorectal tumors. Cancer Res. 1986;46:3543. [PubMed] [Google Scholar]
- 7.Haggerty A, Legler C, Krantz MJ, Fuks A. Epitopes of carcinoembryonic antigen defined by monoclonal antibodies prepared from mice immunized with purified carcinoembryonic antigen or HCT-8R cells. Cancer Res. 1986;46:300. [PubMed] [Google Scholar]
- 8.Harwood PJ, Britton DW, Southall PJ, Boxer GM, Rawlins G, Rogers GT. Mapping epitope characteristics on carcinoembryonic antigen. Br J Cancer. 1986;54:75. doi: 10.1038/bjc.1986.154. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Jensenius JC, Williams AF. The binding of anti-immunoglobulin antibodies to rat thymocytes and thoracic duct lymphocytes. Eur J Immunol. 1974;4:91. doi: 10.1002/eji.1830040207. [DOI] [PubMed] [Google Scholar]
- 10.Köhler M, Milstein C. Continuous cultures of fused cells secreting antibody of predefined specificity. Nature. 1975;256:495. doi: 10.1038/256495a0. [DOI] [PubMed] [Google Scholar]
- 11.Krupey J, Wilson T, Freedman SO, Gold P. The preparation of purified carcinoembryonic antigen of the human digestive system from large quantities of tumour tissue. Immunochemistry. 1972;9:617. doi: 10.1016/0019-2791(72)90247-9. [DOI] [PubMed] [Google Scholar]
- 12.Lowry OH, Rosebrough NJ, Farr AL, Randall RJ. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951;193:265. [PubMed] [Google Scholar]
- 13.Mach J-P, Buchegger F, Forni M, Ritschard J, Berche C, Lumbroso JD, Schreyer M, Girardet C, Accolla RS, Carrel S. Use of radiolabelled anti-CEA antibodies for the detection of human carcinomas by external photoscanning and tomoscintigraphy. Immunol Today. 1981;2:239. doi: 10.1016/0167-5699(81)90011-6. [DOI] [PubMed] [Google Scholar]
- 14.Pimm MV, Baldwin RW. Distribution of IgM monoclonal antibody in mice with human tumour xenografts: Lack of tumour localization. Eur J Cancer Clin Oncol. 1985;21:765. doi: 10.1016/0277-5379(85)90276-7. [DOI] [PubMed] [Google Scholar]
- 15.Price MR, Baldwin RW. Preparation of aminoazo dye-induced rat hepatoma membrane fractions retaining tumour specific antigen. Br J Cancer. 1974;30:382. doi: 10.1038/bjc.1974.212. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Price MR, Brown A, Armitage NC, Baldwin RW. Application of a micro-radioimmunoassay to the analysis of monoclonal antibody-defined epitopes on antigen preparations from human colonic cancer. IRCS Med Sci. 1985;13:366. [Google Scholar]
- 17.Price MR, Edwards S, Baldwin RW. Application of a subcellular membrane-antibody binding assay for the analysis of antigen expression in human tumours. J Cancer Res Clin Oncol. 1986;111:169. doi: 10.1007/BF00400759. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Price MR, Edwards S, Baldwin RW. Association of the Y hapten with glycoproteins, glycolipids and carcinoembryonic antigen in colorectal carcinoma. Cancer Lett. 1986;33:83. doi: 10.1016/0304-3835(86)90104-7. [DOI] [PubMed] [Google Scholar]
- 19.Roe R, Robins RA, Laxton RR, Baldwin RW. Kinetics of divalent monoclonal antibody binding to tumour cell surface antigens using flow cytometry: standardization and mathematical analysis. Mol Immunol. 1985;22:11. doi: 10.1016/0161-5890(85)90029-x. [DOI] [PubMed] [Google Scholar]
- 20.Rogers GT. Carcinoembryonic antigen and related proteins: Molecular aspects and specificity. Biochim Biophys Acta. 1983;695:227. doi: 10.1016/0304-419x(83)90013-6. [DOI] [PubMed] [Google Scholar]