Two mushrooms, Grifola frondosa and Ganoderma lucidum, can stimulate cytokine gene expression and proliferation in human T lymphocytes

Mushrooms have been touted for their immunological potential but few objective data exist. Amongst mushrooms, Grifola frondosa (Maitake mushroom) and Ganoderma lucidum (Reishi mushroom) have been shown to elicit immunological responses in mice. We examined the effects of these two mushrooms on the cytokine gene expression and on the mitogenic response by human peripheral blood mononuclear cells (PBMC) in vitro. The optimal cytokine mRNA stimulation induced by the mushrooms differed between the individual type of mushroom and cytokine examined. Generally, the response to G. lucidum was greater than that to G. frondosa, and the induction of interleukin (IL)-10 and tumor necrosis factor-α (TNF-α) mRNA was greater than that of IL-1β, IL-6 and IL-2. When either of the mushrooms was applied together with phytohemagglutinin (PHA) the relative difference in lymphocyte response to the combination compared to PHA alone was again highly variable among individuals, but was of similar magnitude for both mushrooms. When PBMC were incubated with mushrooms and tritiated thymidine, G. frondosa, but not G. lucidum, induced a dose-dependent increase in proliferation. This research shows that mushrooms are biologically active and can potentiate an immunological response in human lymphocytes in vitro. If such a response also occurs in vivo after consumption of either whole mushrooms or mushroom extracts, it is likely that the physiological state of the consumer will determine whether the response is potentially beneficial or harmful.