In vitro and in vivo immunomodulatory activity of sulfated polysaccharides from Enteromorpha prolifera

Water-soluble sulfated polysaccharides extracted from Enteromorpha prolifera and fractionated using ion-exchange chromatography (crude, F1, F2 and F3 fractions) were investigated to determine their in vitro and in vivo immunomodulatory activities. The sulfated polysaccharides, especially the F1 and F2 fractions, stimulated a macrophage cell line, Raw 264.7, inducing considerable nitric oxide (NO) and various cytokine production via up-regulated mRNA expression. The in vivo experiment results show that the sulfated polysaccharides (the crude and F2 fractions) significantly increased Con A-induced splenocyte proliferation, revealing their potential comitogenic activity. In addition, IFN-γ and IL-2 secretions were considerably increased by the F2 fraction without altering the release of IL-4 and IL-5. This implies that the F2 fraction can activate T cells by up-regulating Th-1 response and that Th-1 cells might be the main target cells of the F2 fraction. These in vitro and in vivo results suggest that the sulfated polysaccharides are strong immunostimulators.