polysaccharides stimulate human monocytes to capture express toll-like receptors 2 and 4, and produce pro-inflammatory cytokines.

BACKGROUND

is a medicinal mushroom with immunomodulatory and antitumor activities attributed to the β-glucans presented in the polysaccharide fraction of its fruiting body. Since β-glucans enhance cellular immunoresponsiveness, in this study we aimed to evaluate the effect of an acid-treated polysaccharide-rich fraction (ATF) of on the ability of human monocytes to adhere/phagocyte yeast cells, their expression of pattern recognition receptors and their ability to produce cytokines.

METHODS

Adhesion/phagocytosis of FITC-labeled was evaluated by flow cytometry. Cells were incubated with specific fluorochrome-labeled antibodies for TLR2 and 4, βGR and MR and also evaluated by flow cytometry. Monocytes were cultured with ATF, and culture supernatants were collected for analysis of in vitro cytokine production by ELISA (TNF-α, IL-1β, IL-12 and IL-10).

RESULTS

ATF significantly increased the adherence/phagocytosis of by monocytes and this was associated with enhanced expression of TLR2 and TLR4, while no effect was observed on βGR or MR. Moreover, expression of TLR4 and TLR2 was associated with higher levels of in vitro production of TNF-α and IL-1, respectively. Production of IL-10 was also increased by ATF treatment, but we found no association between its production and the expression of Toll-like receptors.

CONCLUSION

Our results provided us with evidence that polysaccharides affect human monocytes probably through the modulation of Toll-like receptors.