Abstract: In this study, the immunomodulatory activity of docosahexaenoic acid (DHA) in mouse macrophage RAW264.7 cells was detected by MTT, cell staining, related enzyme activities and Western blot. The MTT assay showed that cell proliferation index reached the maximum level of 73.03% after 48 h of incubation at DHA concentration of 800 ng/mL. The neutral red phagocytosis of RAW264.7 cells was significantly enhanced by DHA. The activation of RAW264.7 cells could be promoted by DHA as observed under scanning electron microscopy. Acrine orange (AO) staining showed that the nucleic acid metabolism of RAW264.7 cell was enhanced by DHA. Periodic acid-Schiff (PAS) staining indicated that DHA promoted the glycogen metabolism and accelerated the differentiation of RAW264.7 cells. Besides, the activities of acid phosphatase, lysozyme and superoxide dismutase were increased by DHA. DHA could increase the phosphorylation of ERK1/2, p38 mitogen-activated protein kinases (MAPKs) and JNK in the MAPKs pathway, indicating that DHA-induced macrophage activation in part depends on the MAPKs pathway. Our results confirmed that DHA had immunomodulatory activity, which will provide a scientific basis for the application of DHA.

Key words: docosahexaenoic acid, RAW264.7 cells, immune regulation, cell proliferation