Interactions of dietary fats and proteins on fatty acid composition of immune cells and LTB4 production by peritoneal exudate cells of rats

The interaction of dietary fats and proteins on lipid parameters of rats wa s studied using safflower oil (linoleic acid-rich), borage oil (gamma -lino lenic acid-rich) or perilla oil (alpha -linolenic acid-rich) in combination with casein or soybean protein. The experiment was focused on the fatty ac id composition of immune cells and the leukotriene B-4 production by perito neal exudate cells. Serum total cholesterol, triglyceride, and phospholipid levels were low in perilla oil-fed or soybean protein-fed rats. Fatty acid compositions of serum and liver phospholipids reflected those of dietary f ats. However, feeding borage oil resulted in a marked increase in the propo rtion of dihomo-gamma -linolenic acid in phospholipids of peritoneal exudat e cells, spleen lymphocytes, and mesenteric lymph node lymphocytes in relat ion to those of liver and serum. It is suggested that activities of metabol ic n-6 polyunsaturated fatty acids are different between immune and other t issues. In addition, the magnitude of the reduction of the proportion of li noleic acid of perilla oil in immune cells was considerably more moderate t han serum and liver, indicating a different degree of interference of or-li nolenic acid with linoleic acid metabolism Leukotriene B-4 release from per itoneal exudate cells was in the order of safflower oil>borage oil>perilla oil groups as reflecting the proportion of arachidonic acid, and tended to be lower in soybean protein-fed groups. These suggest an antiinflammatory p roperty of gamma -linolenic acid as well as alpha -linolenic acid tended to be strengthened when they were combined with soybean protein than with cas ein.