The involvement of O-antigen polysaccharide in lipopolysaccharide in macrophage activation.

Bacterial lipopolysaccharide (LPS), which is generally considered to be an endotoxin, is the major constituent of the outer membrane of Gram-negative bacteria. The structure of LPS consists of three regions; lipid A, core oligosaccharide and O-antigen polysaccharide (O-PS). The structures of lipid A and core oligosaccharide are highly conserved among bacterial genera, but that of O-PS varies and differs in common bacterial species.