Stimulation of mouse peritoneal macrophages by lignin-related substances.

Various lignified materials, including pine cone extract and a commercial lignin, stimulated the morphological change (spreading) of mouse peritoneal macrophages, and their functional maturation as judged by increase in NBT-reducing activity. When these materials were treated with NaClO2 to decompose the phenolic structure, their activity was completely eliminated, whereas the activity was rather enhanced when they were treated with H2SO4 to decompose their sugar moiety. Some monomeric phenolic compounds structurally related to lignin components and several antitumor glucan derivatives had little or no macrophage stimulating activity. The results strongly suggest the importance of lignin-structure in macrophage activation.