The (1→6)-β-d-glucans from Agaricus bisporus and Agaricus brasiliensis were purified to evaluate their effects on the innate immune system. THP-1 macrophages were used to investigate the induction of the expression of TNF-α, IL1β, and COX-2 by RT-PCR. The purification of the polysaccharides gave rise to fractions containing 96-98% of glucose. The samples were analyzed by GC-MS, HPSEC and (13)C NMR, which confirmed the presence of homogeneous (1→6)-β-d-glucans. The β-glucans were incubated with THP-1 derived macrophages, for 3h and 6h to evaluate their effects on the expression of pro-inflammatory genes. Both β-glucans stimulated the expression of such genes as much as the pro-inflammatory control (LPS). When the cells were incubated with LPS+β-glucan, a significant inhibition of the expression of IL-1β and COX-2 was observed for both treatments after 3h of incubation. By the results, we conclude that the (1→6)-β-d-glucans present an immunostimulatory activity when administered to THP-1 derived macrophages.