Reactivity of the human antiendotoxin immunoglobulin M monoclonal antibody HA-1A with lipopolysaccharides from rough and smooth gram-negative organisms.
Clinical data suggest that the human immunoglobulin M antiendotoxin antibody HA-1A reduced mortality in patients diagnosed with gram-negative bacteremia and bacteremia with shock. Previous studies have demonstrated that HA-1A binds to the lipid A domain of lipopolysaccharide (LPS). The present study evaluated the ability of HA-1A to interact with LPs isolated from various strains of gram-negative bacteria by using liquid-phase rate nephelometry and solid-phase immunoblotting assays. HA-1A formed immune complexes in solution with LPSs isolated from both rough and smooth gram-negative organisms. Western blot (immunoblot) analysis of these LPS preparations revealed that HA-1A bound to LPS isolated from rough gram-negative organisms and to a rough LPS-like component present in smooth LPS. HA-1A also bound to LPS-protein complexes found in certain commercial rough LPS preparations. Preincubation of HA-1A with lipid A completely blocked subsequent binding of HA-1A to LPS in both liquid- and solid-phase assay formats, suggesting that the interaction of HA-1A with LPS is through the lipid A domain. Evidence that the binding of HA-1A to LPS was mediated through the antigen-combining (Fv) region of the antibody was provided by the finding that a murine anti-idiotypic antibody to HA-1A inhibited binding. These findings suggested that the broad antiendotoxin reactivity exhibited by HA-1A appeared to be due to the ability of HA-1A to bind to the conserved lipid A moiety of LPSs derived from both smooth- and rough-phenotype gram-negative bacterial strains.
Mascelli
M A
MA
Immunobiology Department, Centocor, Inc., Malvern, Pennsylvania 19355.
Frederick
B
B
Ely
T
T
Neblock
D S
DS
Shealy
D J
DJ
Pak
K Y
KY
Daddona
P E
PE
D000911:Antibodies, Monoclonal / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology*; D001427:Bacterial Toxins / Q000276:immunology*; D015153:Blotting, Western; D004731:Endotoxins / Q000276:immunology*; D006090:Gram-Negative Bacteria / Q000276:immunology*; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D066298:In Vitro Techniques; D008050:Lipid A / Q000276:immunology; D008070:Lipopolysaccharides / Q000276:immunology*; D009391:Nephelometry and Turbidimetry
D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D004731:Endotoxins; D007075:Immunoglobulin M; D008050:Lipid A; D008070:Lipopolysaccharides