Dietary n-3 fatty acids alter murine peritoneal macrophage cytotoxicity

Male CD-1 mice were fed diets containing 10 wt% fat composed of a constant amount of n-6 polyunsaturated fatty acids (PUFA; safflower oil, 1.5 wt%) and increasing levels of n-3 PUFA (up to 1.5 wt%); the remaining fat was a 50:50 mixture of tripalmitin and triolein. Four days prior to sacrifice, the animals were injected intraperitoneally with sterile thioglycollate. Peritoneal macrophages were analyzed for phospholipid fatty acids, prostaglandin E2 (PGE2) synthesis and cytotoxicity towards L929 target cells. Increasing dietary n-3 PUFA increased macrophage phospholipid n-3 PUFA from 4.4 to 11.0 mol% with a concomitant decline in n-6 PUFA from 15.5 to 10.9 mol%, and PGE2 synthesis declined from 2.6 to 1.5 pmol/million cells in thioglycollate-elicited macrophages. Macrophage cytotoxicity toward target L929 cells declined by approximately 50% with increasing n-3 PUFA concentration.