Inhibitory Effect of β-Glucans on Zymosan-Mediated Hydrogen Peroxide Production by Murine Peritoneal Macrophages in Vitro

Abstract

Effects of the pretreatment of murine peritoneal macrophages with several polysaccharides on the production of H₂O₂ induced with unopsonized zymosan were examined. Pretreament with most of (1→3)-β-D-glucans for 6 h at 37°C inhibited the zymosan-mediated H₂O₂ production by macrophages. The phorbol myristate acetate (PMA)-mediated H₂O₂ production was not affected by the pretreatment. The pretreatment of macrophages with (1→3)-β-D-glucans decreased the ability to ingest unopsonized zymosan, but did not affect the ingestion of IgG-coated sheep red blood cells (IgG-SRBC). These results suggested that the pretreatment with (1→3)-β-D-glucans interfered with the interaction of macrophages to zymosan and that the occupation of the receptor for the (1→3)-β-D-glucans inhibited zymosan-mediated production of H₂O₂ by macrophages. Chemical modification by substitution with carboxymethyl groups or hydroxyethyl groups of a (1→6)-branched (1→3)-β-D-glucan reduced the inhibitory effect of pretreatment on zymosan-mediated H₂O₂ production. The above results indicated the possibility that murine peritoneal macrophages possess certain receptors for β-anomeric glucans, and one ligand specificity of the receptors is to restrict the intact (1→3)-β-D-glucosyl back bone.