Abstract
The tumour specific transplantation antigen (TSTA) from a chemically induced rat sarcoma has been isolated as an electrophoretically homogeneous soluble material by affinity chromatography using a Sepharose bound antibody raised to the tumour in syngeneic rats. The TSTA is specific for the particular tumour used (the MC-1 sarcoma) and does not cross-react with material extracted from other rat sarcomata. In addition, a material with different physicochemical properties which cross-reacted with different sarcomata was also eluted from the antibody column and this may be the previously identified onco-embryonic antigen (OEA1) which is immunogenic in the syngeneic host.The purified TSTA labelled with (125)I was used in a radioimmunoassay which detected soluble TSTA in rats bearing a MC-1 sarcoma. The assay shows that tumour transplantation is associated with a persisting release of soluble antigen into the circulation. This antigenic burden is present continuously and renewed as long as the tumour mass exists.
Highlights
The purified transplantation antigen (TSTA) labelled with 125I was used in a radioimmunoassay which detected soluble TSTA in rats bearing a MC-1 sarcoma
We describe here the direct components (Weir and Elson, 1969), but purification of such solubilized TSTA these can be removed by absorption obtained from isolated tumour cell mem- with homogenates from normal rat cells. branes by affinity chromatography, using Contamination with OEA1 or normal
MC-1 tumour is highly immunogenic and (Calbiochem) to approximately 8 ml and does not cross-react with other chemically dialysed against PBS
Summary
Tumours used.-A 20-methylcholanthrene Tris, 0-2 mol/l NaCl, 1 mmol/l EDTA, pH induced sarcoma carried in syngeneic male 8-0 by upward flow. These rats received glycine, pH 7.6) were preincubated with repeated injections at multiple sites of 30 pl of y-globulin or buffer alone and irradiated tumour cells (15,000 rad) over a mixed with 20 ,ul of 20% sucrose and bromoperiod of 3 months. Mata which were syngeneic in male Separation by affinity chromatography with hooded rats and these tumours were desig- Sepharose coupled antibody.-The y-globulin nated MC-9 and MG-Il. Removal of autoimmune antibodies in isolated by ammonium sulphate precipitation syngeneic tumour immune serum by absorp- was linked covalently to cyanogen bromide tion.-Soluble proteins from the 3 mol/l KCG activated Sepharose 4B in a 0-2 mol/l pH extraction of a pool of normal rat organs 6-5, citrate buffer by the method of Cuatrewere cross-linked with glutaraldehyde as casas (1970).
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