Effect of fatty acid modification of cultured hepatoma cells on susceptibility to natural killer cells.

Rat hepatoma (Morris 7777) cells modified with either oleic or linoleic acid exhibited greater susceptibility to normal spleen cell-mediated lysis in a 16-hr 51Cr release assay. At effector:target cell ratios of 300:1, the specific lysis of fatty acid-enriched target cells (cultured for 2 days in fatty acid-supplemented medium) by the normal rat spleen cells was 60% higher than the untreated target cells (P less than 0.01). Prolonging the culture in fatty acid-supplemented medium up to 6 days produced similar effects. Analysis of the fatty acid composition of cellular lipids revealed that an elevation of oleic or linoleic acid was the only significant alteration in the hepatoma cells grown in the oleic or linoleic acid-supplemented medium, respectively. The percentage of the acids was increased in the total cellular phospholipids, the choline, ethanolamine, serine, and inositol phosphoglyceride fractions, and the neutral lipids. In conclusion, we suggest that the elevation of oleic acid and linoleic acid contents in the membranes of the fatty acid-modified hepatoma cells may contribute to the increased susceptibility of these cells to natural killer cell-mediated cytotoxicity.