Inhibitory effect of beta-glucans on zymosan-mediated hydrogen peroxide production by murine peritoneal macrophages in vitro.

Effects of the pretreatment of murine peritoneal macrophages with several polysaccharides on the production of H2O2 induced with unopsonized zymosan were examined. Pretreatment with most of (1-->3)-beta-D-glucans for 6 h at 37 degrees 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)-beta-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)-beta-D-glucans interfered with the interaction of macrophages to zymosan and that the occupation of the receptor for the (1-->3)-beta-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)-beta-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 beta-anomeric glucans, and one ligand specificity of the receptors is to restrict the intact (1-->3)-beta-D-glucosyl back bone.