Humoral reactions in syngeneic hosts against tumor cell surface incomplete saccharide moieties.

Components on the surface of MM2 ascites mammary carcinoma cells induce agglutination factors in the serum of syngeneic host C3H/He mice, and bind the factors in vitro. These components have been classified into three groups: MM2-specific substances, mammary tumor virus (MTV)-associated substances and tumor-associated embryonic materials. The substances contained saccharide moieties and their terminal sugar residues were essential for the binding of the serum factors. These terminal saccharides were exposed during cell proliferation,but masked in stationary cells, at least partly, due to elongation of the saccahride moieits. The terminal structures of these polysaccharide moities of growing and stationary cells were studied by semiquantitative tumor cell agglutination using the agglutinating activities against MM2 cells of MM2-regressor serum and of FMA/R- and Ehrlich-regressor sera which had partial cross-agglutination activities. Agglutination by phytohemagglutinins, inhibition of the agglutination by saccharides or with isolated cell surface components and treatment of the cells with glycosidases were also used for this purpose.