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

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