Biomedical subjects

D M Thomson

Publications and source records attributed to D M Thomson.

94 records · Page 6Linked to original sources

PubMed1973

The presence of tumour-specific membrane antigen in the serum of rats with chemically induced sarcomata.

Antibodies to the tumour-specific transplantation type antigen (TSTA) of a transplanted methylcholanthrene-induced sarcoma (MC-1) in syngeneic rats were studied using the techniques of indirect membrane immunofluorescence and mixed haemadsorption with a (51)Cr-labelled indicator cell. After tumour excision, anti-TSTA antibody was readily measurable in both serum and lymph. In contrast, the tumour-bearing animal had no measurable anti-TSTA antibody in the serum but low titres in the lymph. Consequently, we formed the hypothesis that in the presence of a growing tumour the serum contained antigen-antibody complexes with antigen in excess.To test this hypothesis, tumour-bearing serum was examined for the presence of free antigen and antigen-antibody complexes by 2 different methods. In the first method, tumour-bearing serum was cross-linked with glutaraldehyde and was found to absorb specifically the anti-TSTA antibody, indicating free circulating TSTA. Next, antigen-antibody complexes were split with salt or acid and separated into a low molecular weight (or "antigen") fraction (<100,000) and a high molecular weight (or "antibody") fraction (>100,000). The low M.W. fraction specifically inhibited the anti-TSTA antibody when tested by either membrane immunofluorescence or mixed haemadsorption, indicating the presence of antigen from antigen-antibody complexes in the tumour-bearing circulation. The possible effect on the host's immune response of circulating free tumour antigen and antigen-antibody complexes are discussed.

Animals↗

PubMed1973

A cross-reacting embryonic antigen in the membrane of rat sarcoma cells which is immunogenic in the syngeneic host.

An analysis of the constituents of the plasma membrane of a methylcholanthrene-induced sarcoma (the MC1 tumour) in a hooded rat revealed four tumour-associated macromolecules. Two of these were antigenic in the syngeneic host, one was unique to the MC1 tumour and could not be detected in embryo tissue and has the properties to be expected from the well established tumour-specific transplantation-type antigen while the other, referred to as OEA I, was present in all rat sarcomata tested as well as in early embryos. Two other embryonic components were detected in the sarcoma but these were not immunogenic in the rat. The properties of these tumour-associated "antigens" in the membrane of rat sarcomata are summarized below: [Table: see text]

Animals↗

PubMed1973

Antibodies and soluble tumour-specific antigens in blood and lymph of rats with chemically induced sarcomata.

In confirmation of other studies it has been shown that antibody directed against the tumour specific transplantation-type antigens (TSTAs) cannot be detected in rats with a tumour growing intramuscularly but appears within a few days after excision of the tumour. Circulating antibody is found in the serum of rats with lymph node metastasis following excision of the primary. Absorption by the intramuscular tumour of circulating antibody does not account for the absence of antibody since the antibody levels in thoracic duct lymph in rats with tumours in the leg are also very low and rise rapidly after tumour excision. Antibody is released by the draining nodes directly into the lymph and must pass through the thoracic duct before entering the blood. Under these conditions low levels of antibody activity in lymph cannot be ascribed to absorption by the tumour.It is postulated that TSTA is released from the tumour into the lymph. Following injection of tumour cells into immunized rats the level of antibody falls and this is attributed to release of TSTA from the injected cells. The possible role of antigen release from tumours in determining the host reaction to the tumour is discussed.

Absorption↗

PubMed1969

The radioimmunoassay of circulating carcinoembryonic antigen of the human digestive system.

A radioimmunoassay has been developed for determining the serum levels of carcinoembryonic antigen of the human digestive system in patients with cancer of the colon and rectum. The assay is simple to perform and has a high degree of reproducibility and specificity. The test detects a concentration of 2.5 ng of carcinoembryonic antigen per ml of serum and this has provided the first demonstration of a circulating tumor-specific antigen in the sera of cancer patients.

Adenocarcinoma↗