Inhibitory effects of Agaricus blazei on mast cell-mediated anaphylaxis-like reactions.

Agaricus blazei is a medicinal mushroom native to Brazil. It used to be a source of anti-tumor and immunmoactive compounds and considered a health food in many countries. However, its specific effect against mast cell-mediated anaphylactic reactions is still unknown. In the present study, we investigated the effect of Agaricus blazei water extract (ABWE) on mast cell-mediated anaphylaxis-like reactions. We examined whether ABWE could inhibit systemic anaphylaxis-like reaction, ear swelling response, passive cutaneous anaphylaxis, and mast cell activation. ABWE inhibited compound 48/80-induced systemic anaphylaxis-like reaction, ear swelling response, and passive cutaneous anaphylaxis-like reaction in mice. ABWE also inhibited anti-dinitrophenyl (DNP) IgE-mediated passive cutaneous anaphylaxis. ABWE dose-dependently inhibited compound 48/80-induced or anti-DNP IgE-mediated histamine release from rat peritoneal mast cells (RPMC). Moreover, pretreatment with ABWE reduced compound 48/80-induced calcium uptake into RPMC. When ABWE was added, the level of intracellular cAMP in RPMC showed a significant increase compared with that of control cells. In addition, ABWE significantly inhibited compound 48/80-induced cAMP reduction in RPMC. These results propose that ABWE may be beneficial in the treatment of mast cell-mediated anaphylactic reactions.