Surface protein distributions in cells isolated from solid tumours and their metastases.

Methods have been developed which isolate single viable cells from the primary growths of two tumour systems (a lymphosarcoma and a carcinoma) and their secondary deposits. Subsequent comparisons of the surface-membrane structure of pairs of these primary and secondary cells, using lactoperoxidase-catalysed radioiodination coupled with polyacrylamide-gel electrophoresis, suggest that their overall structures are qualitatively very similar. This latter picture is still maintained when the isolated cells are treated with trypsin or incubated in complete medium before radioiodination. Analysis of the incorporated label into defined sections of the electrophoretic patterns revealed small quantitative differences between primary and secondary cells. In particular, slightly reduced incorporation into certain surface components of secondary cell preparations was seen. However, these did not occur for all the animals investigated, and also they did not consistently occur if the isolated cells were incubated in complete medium. The most similar overall change observed for the two tumour systems was a slight reduction in the secondary cells of a 20K mol. wt surface component.