Effect of Ganoderma lucidum on cytokine release by peritoneal macrophages.

Background: The water-soluble extract of Ganoderma lucidum (Reishi) has been used as an immunomodulator to stimulate spleen cells proliferation and cytokine expression.

Objectives: To investigate the effect of Ganoderma lucidum (G. lucidum) on cytokine production by mice peritoneal macrophages.

Methods: Mice peritoneal macrophages were prepared by intra-peritoneal injection of 5 ml cold PBS. Peritoneal macrophages were plated out at 1X10(6) cell/well in 1ml RPMI 1640 medium supplemented with 10%FCS, 50 microg streptomycin and 50U penicillin. Cells were incubated in the presence or absence of different concentrations of G. lucidum at 37 degrees C and 5% CO2 for 48 hours. Cell free medium was removed and used for cytokine assay by ELISA method (Bender med system).

Results: The results showed no significant differences in cell viability at concentrations ranged from 0-40 microg/ml compared with control group. G. lucidum enhanced IL-1beta, TNF-alpha and NO production in a concentration dependent manner. However, it is not clear if the enhancement of NO release is due to direct effect of G. lucidum on NO synthesis or by indirect endogenous modulation via cytokines. IL-12 release by peritoneal macrophages was also increased in response to different concentrations of G. lucidum, but maximum enhancement was induced in response to 5 microg/ml of G. lucidum (P<0.001).

Conclusion: Our results indicate that G. lucidum at concentrations used has a positive effect on cytokine release and NO production by peritoneal macrophages. Therefore, it is concluded that G. lucidum at moderate concentrations improves macrophage function through cytokine and NO release.