Chemical composition and immunobiological properties of lipopolysaccharide and lipid-associated proteoglycan from Actinobacillus actinomycetemcomitans

Lipopolysaccharide (LPS) and lipid-associated proteoglycan (LPG) were isolated from Actinobacillus actinomycetemcomitans ATCC 29523 by the phenol-water and butanol-water procedures. The LPS was composed of 41 % neutral sugar. 8% hexosamine, 31 % fatty acid, 2% protein, and 2% phosphorus, while the butanol-water-extracted LPG was composed of 13% neutral sugar, 2% hexosamine, 14% fatty acid. 56% protein, and 1% phosphorus. The major fatty acids of LPS and LPG were β-hydroxymyristic, myristic, and palmitic acids. These preparations induced mitogenic and polyclonal responses of LPS-responsive C3H/HeN mouse spleen cells and enhanced in vitro immune responses of the spleen cells to sheep erythrocytes. Spleen cells of C3H/HeJ mouse that were nonresponsive to enterobacteriaceal LPS responded to the butanol-water-extracted LPG, but not to the phenol-water-extracted LPS. The Limulus amebocyte lysate clotting activity of A. actinomycetemcomitans LPS was comparable to that of Escherichia coli K235 LPS. These results indicate that A. actinomycetemcomitans LPS is biologically and immunochemically of Enterobacteriaceae type.