Carcinoembryonic antigen (CEA) "fingerprints"

Extraction of CEA from tumour tissue, foetal colon and patients' sera, and the effect of perchloric acid

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.

[Carcinofetal antigens. III. Further carcinofetal antigens (author's transl)]

The occurrance and significance of important carcinofetal antigens other than AFP and CEA are reported. These included the alpha 2 H-protein which is produced in the liver and increases in serum of patients with various tumors, the fetal sulphoglycoprotein antigen FSA from the gastric juice of patients with gastric cancer, the carcinoplacental alkaline phosphatase (REGAN-isoenzyme)which is found in the serum of patients suffering from e.g. bronchogenic, mammary, urogenital and gastrointestinal carcinomas, the beta-S-fetoprotein which is most likely to be identical with C-reactive protein, gamma-fetoprotein, the carcinofetal antigen in glial tumors (CFGA); ectopic production of placental hormones like human gonadotropin, placental lactogen, plasminogen-activators; leukemia-associated antigens. Furthermore, some other less known carcinofetal antigens are mentioned.