Enhancement of murine alveolar macrophage functions by orally administered beta-glucan

The effect of orally administered SSG, a beta-1,3-glucan obtained from the culture filtrate of the fungus Sclerotinia sclerotiorum IFO 9395, on alveolar macrophage (AM) functions of CDF1 mice was examined. SSG administered orally (20, 40, 80 or 160 mg/kg) for 10 consecutive days enhanced the lysosomal enzyme activity of AM. The greatest enhancing effect was observed at 80 mg/kg of SSG. Multiple oral administrations of SSG (10 consecutive days) were needed to induce significant enhancing effects. Phagocytic activity and interleukin-1 (IL-1) production of AM were also augmented by oral administration of SSG, and the kinetics of the activated state differed depending on the kind of activity. However, H2O2 production of AM was not affected by SSG. Orally administered SSG also (40 or 80 mg/kg, 10 consecutive days) increased the number of AM and the greatest increment was observed 14 days after the first administration. On the other hand, the supernatant of Peyer's patch (PP) cells from mice administered SSG (80 mg/kg) orally stimulated the lysosomal enzyme activity of AM in vitro, and enhanced colony stimulating activity (CSA) was detected from this supernatant. These results demonstrate that SSG given by the oral route can activate murine AM both qualitatively and quantitatively, and it would mediated, at least in part, by the activation of PP cells in the intestine.