We have previously elucidated the precise structure of a unique type of 1,3-beta-D-glucan, AP-FBG (Aureobasidium pullulans-fermented beta-D-glucan), from the fungus A. pullulans and found that AP-FBG strongly induced the production of various cytokines in DBA/2 mouse-derived splenocytes in vitro. However, the mechanism(s) of action of AP-FBG on in vitro mouse primary cells have not been characterized in detail. Herein, we report that: the production of IFN-gamma in DBA/2 mouse-derived splenocytes by AP-FBG was not inhibited following treatment with an anti-dectin-1 neutralizing antibody. In addition, AP-FBG not only failed to activate dectin-1-mediated signaling pathways, examined by a reporter gene assay but also failed to bind to dectin-1, a pivotal receptor for 1,3-beta-D-glucan. Taken together, AP-FBG induced cell activation via dectin-1-independent pathways. (C) 2011 Elsevier Inc. All rights reserved.