Modulation of tumor cell susceptibility to humoral immune killing through chemical and physical manipulation of cellular lipid and fatty acid composition.

Line-10 tumor cells cultured for 24 hr in lecithin-rich normal human plasma or with synthetic lecithin showed a 5- to 8-fold increase in their lecithin:sphingomyelin mole ratio without being affected in their total lipid content or cholesterol:phospholipid mole ratio. These cells were more sensitive to killing by antibody plus complement (C) than untreated controls. Line-10 cells that underwent a homogeneously catalyzed hydrogenation reaction were reduced 6-fold in their content of unsaturated fatty acid compared to controls; the lipid content of these cells was largely unaffected. These cells were more resistant to antibody-C mediated killing than controls. These modifications in cellular lipid and fatty acid composition could be reversed when the cells were recultured for 24 hr in serum-containing tissue culture medium; the cells regained control levels of susceptibility to antibody-C killing at this time. These results suggest that by manipulating the lipid or fatty acid composition of a tumor cell, either indirectly by changing the lipid composition of the environment in which the cell resides or by directly altering the chemical nature of a cellular lipid constituent, the susceptibility of the cell to humoral immune killing can be modulated.