Effects of intraperitoneally administered dietary fibers on superoxide generation from peritoneal exudate macrophages in mice.

To clarify whether edible polysaccharides (dietary fibers) have a host defense stimulating activity, the effects of intraperitoneally administered dietary fiber on the generation of microbicidal superoxide anion (O2-) in mouse peritoneal exudate macrophages (MP) were investigated. MP obtained from mice injected cellulose or pectin generated larger amount of O2- when stimulated by 12-o-tetradecanoylphorbol-13-acetate (TPA) or during phagocytosis of opsonized zymosan than those from mice injected proteose peptone, a widely used elicitor for MP. Especially, generated O2- from cellulose-elicited MP was as strikingly large as that from MP elicited by lentinan, a strong antitumor polysaccharide, when stimulated by TPA. Yeast mannan had no effect on O2(-)-generation. These results suggest the possibility that cellulose and pectin may act as host defense stimulators. The augmentation by cellulose or pectin of O2(-)-generation during phagocytosis was not inhibited by the calmodulin (CaM) antagonist N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7). However, the augmentation was completely disappeared when the protein kinase C (PKC) inhibitor 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7) was added. These results strongly suggest that the augmentation of O2(-)-generation in phagocytosing MP by cellulose or pectin might be due to the increased activity of PKC in the MP, and that CaM may not be involved in the augmentation.