Isolation of three high molecular weight polysaccharide preparations with potent immunostimulatory activity from Spirulina platensis, Aphanizomenon flos-aquae and Chlorella pyrenoidosa

This research describes the identification of three new high molecular weig ht polysaccharide preparations isolated from food-grade microalgae that are potent activators of human monocytes/macrophages: "Immulina" from Spirulin a platensis, "Immunon" from Aphanizomenon flos-aquae, and "Immurella" from Chlorella pyrenoidosa. These polysaccharides are structurally complex and h ave estimated molecular weights above ten million daltons. All three polysa ccharides are highly water soluble and comprise between 0.5 % and 2.0% of m icroalgal dry weight. Immunostimulatory activity was measured using a trans cription factor-based bioassay for nuclear factor kappa B (NF-kappa B) acti vation in THP-1 human monocytes/ macrophages. Using this system the EC50 va lues for these microalgal polysaccharides are between 20 and 110 ng/ml (abo ut 10pM). THP-1 activation was confirmed by measuring immune cytokine mRNA induction using reverse transcriptase-polymerase chain reaction (RT-PCR). E ach polysaccharide substantially increased mRNA levels of interleukin-1 bet a (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha). These polysaccha rides are between one hundred and one thousand times more active for in vit ro monocyte activation than polysaccharide preparations that are currently used clinically for cancer immunotherapy.