We are studying the chemistry cell surface glycoproteins from normal and transformed cells. Our system includes normal cells, transformed cells causing tumors that regress, and transformed cells causing tumors that grow progressively killing the tumor bearer. The transformants causing tumors that kill the host include a line that is immunogenic (preimmunization with irradiated cells protects the host) and a line that in non-immunogenic. Finally, the immunogenic killing line and one of the lines causing tumors that regress share antigens since mice which have rejected challenge by the regressor are protected against the immunogenic progressor. The transformed cells, relative to normal cells, have higher molecular weight glycopeptides. The change is caused by alterations of two different glycoprotein regions (defined by molecular weights). Using a straight biochemical approach and lectin affinity columns we have isolated and purified the altered glycoproteins. Similar techniques coupled with immunologic procedures have allowed us to detect and isolate a unique glycoprotein found on the surface of the cross immunogenic progressor and regressor cells. We are undertaking microchemical characterizations of these glycoproteins. Our goals are to be able to define the carbohydrate structures of cell glycoproteins, and to explore the mechanism of cell surface glycoprotein function in tumor regression.