Abstract
The use of perchloric acid and water for the extraction of CEA from tumour and foetal tissues has been investigated. In the case of tumour, lower recoveries of CEA were obtained from perchloric acid extracts than from aqueous extracts of the same tissue. CEA has also been extracted with 3M KCl solution from insoluble perchloric acid residues of tumour homogenates and cancer patients' serum. Whilst a large proportion of CEA activity recovered from tumour was associated with the perchloric acid residue, the corresponding amounts from serum were very small. CEA elution volumes for each extract, obtained by assay of Sephadex G-200 column fractions, showed significant heterogeneity in molecular size. The purified CEA pools also showed quantitative variations in the binding profiles on Con A-Sepharose. It has been shown that perchloric acid modifies the carbohydrate in CEA, thus altering its Con A-binding properties. Preliminary experiments with foetal colon have demonstrated that, unlike colorectal CEA, a significant proportion of foetal CEA was not bound to ConA. Comparative immunodiffusion showed immunological identity of CEA from the various extracts, although the purified aqueous extract produced an additional precipitin reaction, indicating a second antigen which is relatively unstable or less soluble in perchloric acid.
Highlights
Summary.-The use of perchloric acid and water for the extraction of CEA from tumour and foetal tissues has been investigated
THE preliminary extraction of carcino- (Coligan et al, 1973), molecular size embryonic antigen (CEA) with 1 OM (Coligan et al, 1972) and in its ability to perchloric acid from liver metastases of bind to the lectin concanavalin A (Slayter colonic tumours was described by Krupey and Coligan, 1976). et al (1972) and this method, with minor Despite the widespread use of perchloric modifications, has been largely adopted acid for the isolation of CEA, studies on the by other workers as the initial stage in the possible effect of the acid on the carboisolation of CEA for radioimmunoassay. hydratestructureandheterogeneityof CEA Exclusion chromatography on Sepharose have not been widely reported
The foetal colons were obtained from 26 foetuses aged 15-20 weeks collected over a period of 6 weeks
Summary
The primary colon tumours were obtained surgically and processed immediately. All metastatic tumour and normal colon tissues were necropsy specimens obtained within 24 h of death and generally stored at -20°C until used. The foetal colons were obtained from 26 foetuses aged 15-20 weeks collected over a period of 6 weeks
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