A rapid sensitive monoclonal assay for lipid A in solution.
Lipid A is the toxic component of bacterial endotoxins (LPS) and LPS has been thought to be clinically important in Gram-negative bacterial sepsis, as well as in non-bacteremic states where endotoxemia of enteric origin may be deleterious. The presently accepted method of detecting both LPS and its common lipid A moiety is the Limulus lysate amebocyte assay (LAL), but this test cross-reacts with non-bacterial antigens and serum contains natural inhibitors to the reaction. As an extension of previous work using a polyclonal antibody, we have developed a rapid and sensitive monoclonal antibody assay for lipid A. This 3-step inhibition ELISA is reproducible in aqueous solutions and capable of detecting less than 10 pg/ml of this shared toxic endotoxin component. The assay does not detect intact LPS but acid hydrolysis releases the active lipid A for reaction. While already valuable in detecting lipid A in biological solutions, the presence of naturally occurring anti-lipid A immunoglobulins in serum interfere with the reaction and cause false positives in this inhibition assay. Clinical usefulness of the assay will depend on removal of these antibodies from serum prior to testing.
D000911:Antibodies, Monoclonal; D001360:Avidin; D001439:Bacteroides / Q000032:analysis; D001667:Binding, Competitive; D001710:Biotin; D004306:Dose-Response Relationship, Immunologic; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D000939:Epitopes; D004926:Escherichia coli / Q000032:analysis; D008050:Lipid A / Q000032:analysis*; D008070:Lipopolysaccharides / Q000032:analysis / Q000276:immunology; D012475:Salmonella / Q000032:analysis; D012996:Solutions
D000911:Antibodies, Monoclonal; D000939:Epitopes; D008050:Lipid A; D008070:Lipopolysaccharides; D012996:Solutions; D001360:Avidin; D001710:Biotin