Dietary marine lipid does not alter susceptibility of (NZBxNZW)F1 mice to pathogenic microorganisms.

Female (NZBxNZW)F1 mice were fed for one month with a diet in which the sources of fat were either melted beef tallow or fish oil, the latter regimen being associated with a marked decrease in the expression of auto-immune disease in these animals. To test whether or not this beneficial effect was associated with an increased risk of infection, animals fed each of these diets were challenged intraperitoneally with graded doses of four different classes of microorganisms: a gram positive bacillus that is an intracellular parasite (Listeria monocytogenes), an exotoxin-producing gram negative bacillus (Pseudomonas aeruginosa), a yeast (Candida albicans), and a herpes group virus (murine cytomegalovirus). There was no difference in the susceptibility of the animals fed the two different diets to any of these infections as shown by either determinations of the LD50 for each organism or by assessment of the times of survival for those animals that did succumb. We conclude that the beneficial anti-inflammatory effects of fish oil diets in these mice are not associated with an increased risk of infection with a variety of microbial agents.