Immunological similarity of CEA with alpha 1-acid glycoprotein (orosomucoid) |
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Authors: | Y Ochi Y Fujiyama S Hosoda T Miyazaki M Yoshimura T Hachiya Y Kajita |
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Affiliation: | Department of Clinical Physiology, Glostrup Hospital, 2600 Glostrup, Copenhagen Denmark |
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Abstract: | We have demonstrated that 125 I-CEA (carcinoembryonic antigen) from two commercial sources (Roche and CIS RIA kit) can be precipitated by antibody to alpha 1-acid glycoprotein (AG) dose-dependently. The binding of 125 I-CEA to anti-AG can be displaced by unlabelled AG, though, there was no cross-reaction between AG and anti-CEA. The data strongly suggest that CEA has an immunological similarity to AG. The perchloric acid extract from cancerous tissue was fractionated on a Sephadex G-200 column, and the first eluted fraction (containing large amounts of CEA) was subjected to affinity chromatography using anti-AG bound to Sepharose. The bound fraction was eluted, labelled with 125 I, and then applied to a Sephadex G-200 column with carrier protein. The radioactivity was found mainly in the large molecular size eluted fraction (Fr 1). Almost all radioactivity of Fr 1 was precipitated by anti-AG and anti-CEA. This experiment also demonstrated that a large molecular weight component (Mr: 180 000) obtained from tumor was immunologically related to both CEA and AG. Based on differences in binding affinities between CEA with anti-CEA and with anti-AG we postulate that CEA may be a large molecular precursor of AG (big form of AG). |
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Keywords: | Correspondence: Dr. J. Giese Department of Clinical Physiology Glostrup Hospital DK-2600 Glostrup Copenhagen Denmark. |
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