Conformation dependency of nitric oxide synthesis of murine peritoneal macrophages by β-glucans in vitro

Abstract We have already demonstrated that various activities including NO (nitric oxide) synthesis in vivo were significantly different between triple helical (SPG) and single helical (alkaline-treated SPG, SPG-OH) β-glucans, and that β-glucan-mediated NO synthesis was associated with increased gene expression of IFN-γ. In this study, we analyzed β-glucan-mediated NO production in vitro with the concomitant use of IFN-γ. Proteose peptone-elicited peritoneal macrophages (PM) were collected from male C3H/HeJ mice and cultured with β-glucans in the presence or absence of IFN-γ for 24 h. It was found that SPG-OH, but not SPG, enhanced NO synthesis in vitro, especially in the presence of IFN-γ. Concentrations of interleukin-1α, −6 and TNF-α in the culture supernatant of SPG-OH were significantly higher than those in that of SPG. Membrane-associated IL-1α was also high with SPG-OH. Cytokine productivity of PMs, as well as NO synthesis, was elevated in the presence of IFN-γ. These facts intensely suggest that the single helical conformer of β-glucan (SPG-OH) is dominant in cytokine production and subsequent NO synthesis.