Mushrooms, tumors, and immunity

Borchers AT, Stern JS, Hackman RM, Keen CL, Gershwin ME

Division of Rheumatology/Allergy and Clinical Immunology, University of California at Davis
School of Medicine, Davis, California 95616-8660, USA.

 

Medicinal properties have been attributed to mushrooms for thousands of years. Mushroom
extracts are widely sold as nutritional supplements and touted as beneficial for health. Yet, there
has not been a critical review attempting to integrate their nutraceutical potential with basic
science. Relatively few studies are available on the biologic effects of mushroom consumption,
and those have been performed exclusively in murine models. In this paper, we review existing
data on the mechanism of whole mushrooms and isolated mushroom compounds, in particular
(1-->3)-beta-D-glucans, and the means by which they modulate the immune system and
potentially exert tumor-inhibitory effects. We believe that the antitumor mechanisms of several
species of whole mushrooms as well as of polysaccharides isolated from Lentinus edodes,
Schizophyllum commune, Grifola frondosa, and Sclerotinia sclerotiorum are mediated largely by
T cells and macrophages. Despite the structural and functional similarities of these glucans, they
differ in their effectiveness against specific tumors and in their ability to elicit various cellular
responses, particularly cytokine expression and production. Unfortunately, our data base on the
involvement of these important mediators is still rather limited, as are studies concerning the
molecular mechanisms of the interactions of glucans with their target cells. As long as it remains
unclear what receptors are involved in, and what downstream events are triggered by, the binding
of these glucans to their target cells, it will be difficult to make further progress in understanding
not only their antitumor mechanisms but also their other biological activities.

 

Table of Contents

 

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