We investigated the effect of 2,3-dibenzylbutane-1,4-diol (DBB), a mammalian lignan, on superoxide production and [Ca2+]i mobilization in human neutrophils. DBB did not generate superoxide production by itself, but enhanced the FMLP or A23187-induced superoxide production in a dose dependent manner. DBB did not influence the OAG-induced superoxide production. The priming effect of DBB was inhibited by W-7 or trifluoroperazine, but not by H-7 or staurosporine. And the priming effect of DBB was observed in the presence or absence of extracellular Ca2+. DBB enhanced the low dose FMLP-induced [Ca2+]i mobilization. These results suggest that the priming effect of DBB in human neutrophils may be caused by the activation of the calcium-calmodulin pathway but not the protein kinase pathway.