Effect of alpha-linolenic acid on the metabolism of omega-3 and omega-6 polyunsaturated fatty acids and histamine release in RBL-2H3 cells.

We examined the effect of alpha-linolenic acid (18:3 (n-3)) pretreatment on the metabolism of omega-3 and omega-6 polyunsaturated fatty acids and histamine content and release of RBL-2H3 cells. RBL-2H3 cells grew without reduction in number when incubated with subculture media for 3 d and then placed again in serum-free medium with bovine serum albumin (BSA) and epidermal growth factor (EGF). Cholesterol pullulan (10 micrograms/ml) emulsified alpha-linolenic acid (20 micrograms/ml) was recommended as an additional form serum free medium. We determined the fatty acid composition in all neutral lipids, free fatty acids and all phospholipids in alpha-linolenic acid-treated cells. In all cases the concentration of alpha-linolenic acid and docosahexenoic acid (DHA, 22:6 (n-3)) was increased, while linolenic acid (18:2 (n-6)) was slightly and arachidonic acid (20:4 (n-6)) was markedly decreased. Content of histamine in alpha-linolenic acid-treated cells was remarkably lower than that of untreated cells. Accordingly, net histamine release stimulated by antigen or A23187 was also markedly decreased in the alpha-linolenic acid-treated cells, as was the percent histamine release stimulated by antigen. Results from our in vitro experiment suggest that the anti-allergic effect of alpha-linolenic acid may be caused either by the decrease in histamine content or by inhibition of the release of chemical mediator resulting from changes in the fatty acid composition.