Abstract: 　Objective To investigate the signaling role of arachidonic acid in the invasion of RAW264.7 macrophage by Toxoplasma gondii . Methods Rate of infection was calculated by both light microscope and flow cytometer. Fluorescent emission spectra were recorded using a microspectrofluometer for the concentration of cytoplasmic free calcium. Results Calcium concentration in macrophages and rate of infection increased with a higher concentration of exogenous arachidonic acid in a dose-dependent manner. The invasion was dependent on the mobilization of calcium from the extracellular medium and from intracellular stores and followed the influx of calcium into the parasitized cell. Conclusion Arachidonic acid may enhance the rate of infection via calcium transduction pathway.

Key words: Toxoplasma gondii, invasion, macrophage, arachidonic acid, calcium signal