Lipopolysaccharides of reduced toxicity and the production thereof

Abstract

An acyloxyacyl hydrolase from the human promyelocyte cell line HL-60 has been found to specifically hydrolyze fatty acids form their ester linkages to hydroxy groups of 3-hydroxyfatty acids, the latter being bound in turn to LPS glycosaminyl residues. The hydrolyzed fatty acids may include dodecanoic acid, tetradecanoic acid and hexadecanoic acid. This enzyme showed a molecular weight between about 50,000 daltons and about 70,000 daltons. Altered bacterial LPS substantially without fatty acids bound in ester linkage to hydroxy groups of 3-hydroxyfatty acids covalently linked to a glucosaminyl moiety of LPS lipid A are produced. Since the structure of the lipid A moiety is highly conserved, acyloxyacyl hydrolase may act on LPS of many different pathogenic bacteria (for example Salmonella, Escherichia, Hemophilus, and Neisseria). Such altered bacterial LPS, having toxicity reduced more than immunostimulatory activity, may be therapeutically useful: (1) as vaccines to prevent Gram-negative bacterial diseases by inducing antibodies to LPS 0-polysaccharide or R-core antigens, (2) as antidotes to treat or prevent gram-negative bacterial sepsis ('septic shock'), or (3) as adjuvants to enhance formation of antibodies to other antigens. The acyloxyacyl hydrolase itself may be therapeutically useful to detoxify endogenous LPS in patients with gram-negative bacterial diseases or to remove toxic LPS from therapeutic injectants.