Dietary immune-modulation – carbohydrate specific effects of cereal and yeast -glucans

High intake of dietary fiber is claimed to protect against development of colorectal cancer. Barley is a rich source of dietary fiber, and possible immunomodulatory effects of barley polysaccharides might explain a potential protective effect. Dietary fiber was isolated by extraction and enzyme treatment. A mixed-linked -glucan (WSM-TPX, 96.5% -glucan, Mw 886 kDa), an arabinoxylan (WUM-BS-LA, 96.4% arabinoxylan, Mw 156 kDa), a mixed-linked -glucan rich fraction containing 10% arabinoxylan (WSM-TP) and an arabinoxylan rich fraction containing 30% mixed-linked -glucan (WUM-BS) showed no significant effect on IL-8 secretion and proliferation of two intestinal epithelial cell lines, Caco-2 and HT-29, and had no significant effect on the NFB activity in the monocytic cell line U937-3 B-LUC. Further enriched arabinoxylan fractions (WUM-BS-LA) from different barley varieties (Tyra, NK96300, SB94897 and CDCGainer) were less active than the mixed-linked -glucan rich fractions (WSM-TP and WSM-TPX) in the complement-fixing test. The mixed-linked -glucan rich fraction from NK96300 and CDCGainer showed similar activities as the positive control while mixed-linked -glucan rich fractions from Tyra and SB94897 were less active. From these OPEN ACCESS Int. J. Mol. Sci. 2011, 12 571 results it is concluded that the isolated high molecular weight mixed-linked -glucans and arabinoxylans from barley show low immunological responses in selected in vitro test systems and thus possible anti-colon cancer effects of barley dietary fiber cannot be explained by our observations.