Comparative effect of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids on neutrophil function

Experiments were performed in neutrophils isolated from Wistar male rats (200 ± 20g). The toxicity of fatty acids was tested using flow cytometry. The quantification of H 2 O 2 was assessed by phenol red in basal conditions and after stimulation with PMA (Phorbol Myristate Acetate). Production of O 2 •− was determined by using lucigenin chemiluminescence. Within four hours, DHA induced loss of plasma membrane integrity in a concentration of 250 μM and EPA from 300 μM. EPA had no effect on DNA fragmentation at 200 μM whereas the DHA had a significant effect from 150 μM. Production of H 2 O 2 in cells treated with EPA and DHA was increased from 25 μM. When stimulated with PMA, this increase was seen with EPA only. The production of O 2 •− was increased from 50 μM DHA and from 100 μM to EPA; these increases were dose dependent. To determine the involved route of ROS production, inhibitors such as antimycin, etomoxir and apocynin were used. Only the latter, which inhibits NADPH oxidase, decreased ROS production induced by the phagocytes. These findings indicate that DHA was more toxic than the EPA after 4 hours of treatment. Both EPA and DHA stimulated the production of H 2 O 2 and O 2 •− in neutrophils, and this effect occurred via activation of NADPH oxidase. Financial support: FAPESP