Assay of anti-endotoxin antibodies

Lipopolysaccharides (LPS) constitute components of the outer membrane of Gram-negative bacteria. Chemically, they consist of a heteropolysaccharide and a covalently linked lipid, termed lipid A. The polysaccharide region is made up of the O-specific chain (built from repeating units of three to eight sugars) and the core part, divided into the inner core (the part linked to the lipid) and the outer core (the part linked to the O-specific chain). LPSs possessing an O-specific chain are called smooth LPS (S-LPS), those not having an O-chain are termed rough (R-LPS). The latter type of LPS may be observed in mutants that have lost the ability to synthesize the O-chain, or in wild-type bacteria without known genetic defect. LPS also represent the endotoxin of Gram-negative bacteria. In mammals, including humans, LPS exhibits a variety of biological effects that may be beneficial if administered in low amounts but harmful when present in higher concentrations as in the case of Gram-negative infection and Gram-negative septicemia.