INHIBITORY EFFECT OF BETA-GLUCANS ON ZYMOSAN-MEDIATED HYDROGEN-PEROXIDE PRODUCTION BY MURINE PERITONEAL-MACROPHAGES INVITRO

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)-beta-D-glucans for 6h 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.