Lipopolysaccharides (LPS) located to the outer leaflet of the outer membrane have been identified as the main common endotoxic component of Gramnegative bacteria (1-3). Although other constituents of the bacterial cell wall, i.e., peptidoglycan, may contribute, LPS is considered to be the single most important constituent of Neisseria meningitidis that induces inflammation in the host (4-12). Neisserial lipopolysaccharides are often referred to as lipooligosaccharides (LOS) owing to the short polysaccharide chains comprising approx 10 sugars or less that are attached to lipid A.