Specific recognition of immune cytokines by sulphated polysaccharides from marine algae

Several immune cytokines, including interleukin-2 (IL-2), interleukin-7 (IL-7) and gamma interferon (INF-y), have been shown to interact with the sulphated polysaccharides heparin and heparan sulphate, so that the co-administration of cytokines with such sulphated sugars may improve current cytokine-based therapies. In this study, sulphated polysaccharides were extracted from the green alga Codium fragile in cold water and purified by size exclusion chromatography. Gas chromatography-mass spectroscopy indicated that they were galactans and/or arabinogalactans, and preliminary nuclear magnetic resonance spectroscopy analysis suggested that they consisted of repeating units of several monosaccharide residues, probably galactopyranose and arabinopyranose, which were sulphated. The binding of Codium fragile polysaccharide and commercial preparations of fucoidan, carrageenans and heparin to IL-2, IL-7 and INF-y was then assessed using an ELISA-based inhibition test. For all cytokines tested, inhibition by fucoidan was found to be strongest (80-90% inhibition), followed by heparin (65-80% inhibition), the Codium polysaccharide (40-59% inhibition) and finally the carrageenans (20-60% inhibition). The differential binding profiles obtained for the cytokines tested suggest the interactions between cytokines and sulphated polysaccharides are specific and could therefore be exploited in a therapeutic capacity.