Determination of 2-keto-3-deoxyoctanate: a simple method for the quantitative comparison of cytokine induction by meningococcal lipopolysaccharide and that of other bacteria

Abstract

Abstract Background Lipopolysaccharide (LPS), or endotoxin, is considered to be the toxic element in Gram-negative septic shock. There is increasing evidence that the pathogenic properties of LPS differ from species to species but, to date, exact comparison between the biological activities of LPS has been difficult. Methods With the aim of quantitatively comparing the cytokine-inducing capacities of Neisseria meningitidis LPS and Escherichia coli LPS in human peripheral blood mononuclear cells on a molar basis, 2-keto-3-deoxyoctanate (KDO) spectrophotometry was used. Results Since the KDO region of LPS is a preserved part of the LPS molecule, unlike the saccharide tail, and the molecular weight of this region is known, KDO measurement can provide accurate information about the molarity of an LPS suspension. On a molar basis, the cytokine-inducing capacity of meningococcal LPS was at least ten times higher than that of E. coli LPS. Conclusion KDO spectrophotometry is a simple method of making a quantitative comparison between the biological effects of different endotoxins. N. meningitidis LPS is a more potent inducer of cytokine production than E. coli LPS. This may, in part, explain the more fulminant course of meningococcal sepsis compared with E. coli sepsis.