title: IFN-gamma primes macrophages for enhanced TNF-alpha expression in response to stimulatory and non-stimulatory amounts of microparticulate beta-glucan.
abstract: beta-(1-->3)-D-Glucan is an integral cell wall component of a variety of fungi, plants, and bacteria. Like the prototypic inflammatory mediator lipopolysaccharide (LPS), some beta-(1--> 3)-D-glucan-containing preparations have been shown to induce the production of proinflammatory cytokines by macrophages. In the present study, we have tested a new microparticulate form of beta-(1--> 3)-D-glucan (MG) from Saccharomyces cerevisiae for its ability to induce proinflammatory cytokine secretion in mouse peritoneal macrophages in vitro, and we have examined the effect of IFN-gamma. MG was rapidly phagocytized by peritoneal macrophages, and these MG-treated macrophages upregulated TNF-alpha, IL-6, and IL-1beta mRNAs and secreted these proinflammatory cytokines. IFN-gamma treatment alone did not induce unstimulated macrophages to produce TNF-alpha. However, a 4 h IFN-gamma pretreatment augmented TNF-alpha secretion by peritoneal macrophages subsequently treated with an optimally stimulatory dose of MG. IFN-gamma pretreatment for 2 h followed by thorough washing and a further 2 h incubation without IFN-gamma still resulted in enhanced TNF-alpha production in response to MG, suggesting that IFN-gamma can prime macrophages for a subsequent proinflammatory response. Most interestingly, we found that IFN-gamma pretreatment of peritoneal macrophages enhanced the TNF-alpha response to amounts of MG that were poorly stimulatory or non-stimulatory in the absence of IFN-gamma priming. These data suggest that a synergy between IFN-gamma and beta-glucan may have evolved to lower the threshold of sensitivity of the innate immune response to fungal pathogens.
authors.affiliation: Department of Microbiology and Immunology, University of Nevada School of Medicine, Applied Research Facility, MS-199, Reno, NV 89557, USA.
authors.forename: Mathew D
authors.initials: MD
authors.lastname: Berner
authors.forename: Michael E
authors.initials: ME
authors.lastname: Sura
authors.forename: Bryce N
authors.initials: BN
authors.lastname: Alves
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Hunter
mesh_terms: D000818:Animals; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D007371:Interferon-gamma / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism; D017737:Macrophages, Peritoneal / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D010587:Phagocytosis / Q000502:physiology; D011509:Proteoglycans; D012333:RNA, Messenger / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*; D047071:beta-Glucans / Q000378:metabolism*
chemical_list: D016207:Cytokines; D008070:Lipopolysaccharides; D011509:Proteoglycans; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D047071:beta-Glucans; C010770:polysaccharide-K; D007371:Interferon-gamma