The Differential Immunomodulating Effects of Levan and DFA-Ⅳ on Macrophage Function

Di-D-fructose-2,6':6,2'-dianhydride (DFA-Ⅳ) is a disaccharide consisting of two fructose residues that are prepared from levan by levan fructotransferase. Levan is a homopolysaccharide composed of D-fructofuranosyl residues joined by β-(2,6) and β-(2,1) linkages. We compared the immunomodulatory effects of levan with DFA-Ⅳ. Tumoricidal activity, phagocytosis and nitric oxide (NO) production were examined in levan- and DFA-Ⅳ-treated RAW264.7 cells. The NO production, tumoricidal and phagocytic activities were significantly increased in both treated cells. The results indicate that levan has significantly greater effects on tumoricidal activity than DFA-Ⅳ at low concentrations (1 ㎍/mL) and its effect on NO production shows a similar pattern. These results suggest that tumoricidal activity induced by both samples is mediated by NO production.