Radioimmunological characterization of carcinoembryonic antigen (CEA) preparations.

A multi-step radioimmunological test system was applied to the characterization of carcinoembryonic antigen (CEA) preparations obtained by column chromatography including ion exchange procedure. CEA contents were estimated by means of a sequential inhibition radioimmunoassay using Protein A-bearing Staphylococci for coprecipitation. Data were expressed as "units CEA" and compared with results obtained from commercial CEA-RIA kits. In addition, attempts were made to evaluate the presence of normal cross-reacting antigens in CEA preparations by the application of an antiserum to perchloric acid extract from normal lung tissue. Data from these tests were expressed as "units NLA" (NLA stands for "normal cross-reacting lung antigen"). The factor "units CEA/units NLA" proved useful as an indication of the tumour specificity of those antigenic components measured in the inhibition assay. Moreover, radioimmunoprecipitation tests with subsequent SDS polyacrylamide gel electrophoretic analysis were performed in order to get information on the molecular weight of the molecule(s) involved in the radioimmunological CEA determination procedure. The test system displayed 1) highly specific CEA reagibility in the standard inhibition assay, 2) test sensitivity of about 200 pg CEA (when related to the Hoffman/La Roche test) and 1 ng CEA (when related to CEA-IRE-SORIN), 3) low reagibility to normal cross-reacting antigens, also when compared to the commercial tests, 4) a molecular weight of about 200,000 daltons for the component(s) measured, and 5) evidence of inhomogeneity of the CEA batches investigated and those international references available. The latter might in part be attributed to so-called species-specific CEA-related determinants. The test system proved also useful for CEA estimations in crude tissue extracts.

Is there any diagnostic relevance of human antibodies which react with mouse mammary tumor virus (MuMTV)?

Applying an indirect immunofluorescence assay with prolonged serum incubation on frozen-cut mouse mammary tumor slices, antibodies are detectable in human sera which react with viral inclusion bodies consisting of intracytoplasmic A particles (iAp). These iAp are known to represent intracellular entities of the mouse mammary tumor virus (MuMTV), mainly related to MuMTV core constituents. In 1,449 women studied, the antibody incidence is partially correlated with proliferating changes of the mammary gland. However, epidemiological data obtained thus far have clearly shown that the detection of antibody is not useful in breast cancer diagnosis (antibody incidence in breast cancer patients 22.8%, in lactating women 20.6%, in controls 5.9%). Studying antibody reagibility to particular iAp polypeptides by means of a radioimmunoprecipitation (RIP) technique, there has been preliminary evidence that human serum factors react with more than one mouse virus protein. The most prominent reactivity was seen to be directed to the 14,000 dalton protein (Ap14). The detection of serum antibody activity is considered as being of important indicative value in that it reflects the existence of MuMTV-related antigens in man.

Radioactivity in gastric juice-a simple adjunct to the Yb-169 DTPA cisternographic diagnosis of CSF rhinorrhea: concise communication.

A new method is offered as an adjunct to radionuclide cisternography and the measuring of radioactivity in nasal pledgets. The activity in gastric juice following the intrathecal injection of Yb-169-DTPA is measured and the ratio of gastric juice to blood is calculated. In patients suffering from CSF rhinorrhea the ratios significantly exceed the normal range. This method can be used to detect CSF leakage at the back of the nasopharynx, and in patients with head injuries too severe to permit the use of nasal pledgets.

Further evidence for common antigens in intracytoplasmic A particles of mouse mammary tumors and B type virions of murine milk.

Using the indirect immunofluorescence technique and radioimmunoprecipitation test (RIP test) according to ABELEV and ELGORT (1970) immunological investigations intracytoplasmic A particles isolated from mouse mammary tumors were performed. In order to purify the virus particles sucrose gradients were employed according to TANAKA et al. (1972) and in some details according to SMITH and WIVEL (1973). In immunofluorescence studies on mammary tumor slices a complete cross-reaction between antisera against A particles from mammary tumors and MTV-B particles from mouse milk was observed. Both kinds of antisera reacted in identical fluorescence pattern types with intracytoplasmic A particle clusters and with extracellular accumulations of B type virions, respectively, in tumors of different histological structures. RIP test studies suggest that these cross-reactions are attributed to three common antigens in A and B type viruses. Thus, there does not remain any doubt that intracytoplasmic A particles in murine mammary tumors are MTV-related. All these A particles antigens were identically detected using an antiserum against A particles isolated from mouse leukemia cells (serum kindly provided by Dr. TANAKA). The biological role of intracytoplasmic A particles in mouse tissues is discussed. In contrast to the precursor theory, it is believed that they could represent something like a nonsense way of particle maturation in MTV-infected cells.