Induction of nitric oxide production in RAW264.7 cells under serum-free conditions by O-antigen polysaccharide of lipopolysaccharide

Anticancer Res. 2013 Jul;33(7):2875-9.


Background: Lipopolysaccharide derived from Pantoea agglomerans (LPSp) mainly consists of two aggregates, the high-molecular aggregate (HMM-LPSp) and the low-molecular aggregate (LMM-LPSp). The structural differences between HMM-LPSp and LMM-LPSp seem to depend on the length of the O-antigen polysaccharide because the lipid A regions of the two fractions are quite similar. In this study, we examined the biological activity of LPSp focusing on the O-antigen polysaccharide using HMM-LPSp and LMM-LPSp under serum-free conditions.

Materials and methods: The binding of LPSp to RAW264.7 cells under serum-free conditions was analyzed by flow cytometry using LPSp-conjugated fluorescein isothiocyanate (FITC-LPSp). The biological activities of HMM-LPSp and LMM-LPSp under serum-free conditions were evaluated by the nitric oxide production.

Results: FITC-LPSp showed higher fluorescence intensity under serum-free than serum-containing conditions. HMM-LPSp induced higher nitric oxide production than LMM-LPSp under serum-free conditions.

Conclusion: The present study indicates that the reactivity of LPSp is affected by the O-antigen polysaccharide under serum-free conditions.

Keywords: HMM; LMM; LPS; LPSp; O-antigen polysaccharide; Pantoea agglomerans; serum-free.

MeSH terms

  • Animals
  • Cells, Cultured
  • Culture Media, Serum-Free / pharmacology
  • Flow Cytometry
  • Lipopolysaccharides / immunology
  • Lipopolysaccharides / pharmacology*
  • Macrophages / immunology
  • Macrophages / metabolism*
  • Mice
  • Nitric Oxide / metabolism*
  • O Antigens / immunology*
  • O Antigens / metabolism
  • Pantoea / metabolism*


  • Culture Media, Serum-Free
  • Lipopolysaccharides
  • O Antigens
  • Nitric Oxide