Inhibitory Effects of Water-Soluble Low-Molecular-Weight β-(1,3-1,6) D-Glucan Isolated from Aureobasidium pullulans 1A1 Strain Black Yeast on Mast Cell Degranulation and Passive Cutaneous Anaphylaxis

We investigated the effects of water-soluble low-molecular-weight beta-(1,3-1,6) D-glucan isolated from Aureobasidium pullulans 1A1 strain black yeast (LMW-beta-glucan) on mast cell-mediated anaphylactic reactions. Although it is known that LMW-beta-glucan has anti-tumor, anti-metastatic and anti-stress effects, the roles of LMW-beta-glucan in immediate-type allergic reactions have not been fully investigated. We examined whether LMW-beta-glucan could inhibit mast cell degranulation and passive cutaneous anaphylaxis (PCA). LMW-beta-glucan dose-dependently inhibited the degranulation of both rat basophilic leukemia (RBL-2H3) and cultured mast cells (CMCs) activated by calcium ionophore A23187 or IgE. However, LMW-beta-glucan had no cytotoxicity towards RBL-2H3 cells and CMCs. Furthermore, orally administered LMW-beta-glucan inhibited the IgE-induced PCA reaction in mice. These results show LMW-beta-glucan to be a possible compound for the effective therapeutic treatment of allergic diseases.