Effects of alpha-glucans from Agaricus bisporus on ex vivo cytokine production by LPS and PHA-stimulated PBMCs; a placebo-controlled study in slightly hypercholesterolemic subjects.

BACKGROUND

Mushrooms are known for their immune modulating effect for which the polysaccharide fraction, mainly glucans, seem to be responsible. Fungal beta-glucans have been studied extensively, whereas little is known about mushroom alpha-glucans. We have earlier shown that the polysaccharide fraction from the mushroom A. bisporus, consisting 90% of alpha-glucans, induced in vitro tumor necrosis factor (TNF)alpha and nitric oxide production. The purpose of this study was to evaluate the effects of consuming.

METHODS

A. bisporus alpha-glucan on ex vivo cytokine production by human peripheral mononuclear blood cells (PBMCs). A double-blind randomized trial was designed in which 56 mildly hypercholesterolemic subjects consumed a control fruit juice with no added alpha-glucans (200 ml/day) for a 2-week run-in period. For the next 5 weeks, the control group (N=30) continued consumption of the control fruit juice, whereas the intervention group (N=26) consumed the same fruit juice enriched with alpha-glucans from A. bisporus (5 g glucans/day). Changes in interleukin (IL)-1beta, IL-6 and TNFalpha cytokine production by lipopolysaccharide (LPS)-stimulated PBMCs were evaluated, as well as changes in T-helper (Th)1/Th2 cytokines by phytohemaggutinin (PHA)-stimulated PBMCs.

RESULTS

Consumption of A. bisporus alpha-glucans lower LPS-induced TNFalpha production by 69% (P=0.017) as compared with the control group, whereas no effect on IL-1beta and IL-6 was observed. No obvious Th1-Th2 skewing by PHA-stimulated PBMCs was observed. However, we observed a trend towards a decreased production of IL-12 and IL-10.

CONCLUSIONS

Our current finding suggests that in vivo, alpha-glucans have lost their efficacy to stimulate the immune response as observed in our in vitro mouse model.