But when studies revealed that antitoxin reacted equally well with washed cells as culture filtrate, it was realized that the bacteria underwent autolysis during growth and released parts of their cell walls in a soluble form.> Mayor toxin of N. meningitidis is its lipopolysaccharide, LOS, and its mechanism is endotoxic.> Important determinant of virulence of N. meningitidis is its antiphagocytic polysaccharide capsule.">