V. V. Kalashnikov

HUMAN EMBRYONIC PREALBUMIN AS A MARKER FOR TUMOURS AND FIBROBLASTS

Embryonic prealbumin (E.P.A.) was demonstrated by agar immunodiffusion in 122 out of 505 homogenates of various tumours and in 7 out of 20 serum samples from patients with connective-tissue tumours. Analogous antigen was found in human embryonic and adult cultured fibroblasts. This newly identified antigen is probably actively secreted by fibroblasts into the circulation of patients with tumours.

Physical and Chemical Properties of Human Embryonic Prealbumin and its Association with Malignancies

Human embryonic prealbumin (EPA) was purified from pooled fetal sera by a combination of the salt precipitation methods, ion‐exchange chromatography and electro‐isofocusing. Purified EPA preparations had about 80% peptide and 20% carbohydrate including mannose, fucose, glucose, galactose, glucosamine and galactosamine. Amino acid composition of EPA may be characterized by high concentration of aspragin. glutamine acids and proline but very low concentration of methionine.

Immunochemical identification of carcinoembryonic antigen in extracts of ovarian adenocarcinoma and pseudomucinous cystoma

Carcinoembryonic antigen (CEA) was found in 3 of 17 individual extracts of adenocarcinoma and in 7 of 8 individual samples of a pseudomucinous cystoma of the human ovaries. Rabbits were immunized with the separate fractions (ammonium sulfate, sulfosalicylic acid, and phosphotungstic acid) of CEA-positive ovarian adenocarcinomas in order to obtain specific antisera against CEA.

Immunochemical identification of a new embryonic antigen in ovarian tumor tissue

A new embryonic antigen was found in ovarian tumors by methods of immunodifusion analysis. This antigen consists of two components with different electrophoretic mobilities: The slow peak migrates in the αo-globulin zone, the fast peak in the prealbumin zone. It is immunologically different from α-fetoprotein and from the carcinoembryonic antigen of the large intestine. The antigen was found in fetal and neonatal blood serum and also in, tissue extracts of ovarian tumors. It was not found in normal adult human tissues or in the blood serum of healthy donors and cancer patients.

Paraneoplastic phenotype of human gastric glands studied with the AID of CEA of the specific lectin crustacin

With modern methods of investigation the dynamics of changes in the mucous membrane can be studied in sufficient detail during carcinogenesis of the human gastric epithelium [5]. However, it is important to note that not all the details of the morphological and functional state of the mucous membrane can be analyzed equally thoroughly. For instance, virtually no attention has been paid to the study of the phenotype of the specialized gastric glands which remain in loci of intestinal metaplasia of the mucous membrane, with or without the presence of carcinoma or other malignant neoplasms. The aim of this investigation was to study morphological and functional characteristics of the gastric glands. The main research tool used in the investigation was the lectin crustacin (Cr), which can react specifically with the carbohydrate component of carcinoembryonic antigen (CEA) [1, 3, 4].

Immunohistochemical study of carcinoembryonic antigen (CEA) in normal and embryonic human tissues using the CEA-specific oncoprecipitin “crustacin”

Using immunoperoxidase technique, antibodies to CEA (Ab) were compared to a glycoprotein krustacin (Kr) extracted from Pagurus prideauxii, which has an ability to precipitate specifically CEA. It was found that Kr and Ab reacted in a similar manner with embryonic and normal gastrointestinal tissues, revealing practically identical localization of the antigen in the tissues and cells. It was possible, however, to note some quantitative and qualitative differences in the distribution of antigen, which showed that Kr and Ab reacted with different determinants of the CEA molecule.

Immunohistochemical study of carcino-embryonic antigen (CEA) in human tumors using crustacin, a CEA-specific oncoprecipitin

This paper gives the results of a study of human tumors by immunohistochemical methods using a CEA-specific oncoprecipitin, crustacin (CR) by comparison with the use of anti-CEA antibodies (AB). It was shown previously that CR gives a reaction of antibody type with CEA [I]. CR and AB reveal closely related determinants in embryonic and normal human tissues [5], epitopes for CR (CEA-CR) being more embryo-specific than those for AB (CEA-AB). Structural differences may perhaps exist in some of the determinants revealed with the aid of AB and CR.

An analog of human embryonic prealbumin-1 in animals

The discovery of analogs of human embryonic proteins in the blood of animals provides fresh opportunities for the study of these proteins both in embryogenesis and in carcinogenesis on experimental models. One such embryonic protein is embryonic prealbumin-i (EPAi), which is a glycoprotein [5]. EPA-I was first found in amniotic fluid and in the blood serum of human fetuses [2, 3, 6], in tissue extracts of various tumors, and also in cultures of embryonic and adult fibroblasts [i, 2, 6, 7].

Analogs of human embryonic prealbumin-2 in animals

The cellular localization of EPA-2 in tissues of calf fetuses and adult animals was studied by the indirect immunofluorescence analysis method. Tissue sections 4-8 ~ thick were fixed with alcohol and acetic acid [7] and embedded in paraffin wax [8]. The sections were labeled by means of antibodies against EPA-2 obtained with the aid of an immunosorbent. EPA-2 immobilized on ACA-34 ultrogel by means of glutaraldehyde [6] was used as the immunosorbent. The technique of immunofluorescence analysis was described by the writers previously [2]. To study analogs, amniotic fluid, tissue, and blood serum from fetuses in the first half of embryonic development, and tissue and blood serum from adult animals were chosen. The tissue extracts were prepared in Tris-glycine buffer, pH 8.3, with the addition of detergents [4].

Biosynthesis of embryonic prealbumin by cultured human fibroblasts

Embryonic prealbumin (EPA) was found in human fibroblasts by immunodiffusion and immunofluorescence analysis. No quantitative or qualitative differences in the content and localization of this antigen were found between embryonic and adult human fibroblasts. It is concluded that human fibroblasts synthesize EPA, which can be used as a marker for cells of this type.