Complement Activation Induced by Purified Neisseria meningitidis Lipopolysaccharide (LPS), Outer Membrane Vesicles, Whole Bacteria, and an LPS‐Free Mutant

Universitetet i Tromsø, Tromsø, Troms, Norway
The Journal of Infectious Diseases (Impact Factor: 6). 02/2002; 185(2):220-8. DOI: 10.1086/338269
Source: PubMed


Complement activation is closely associated with plasma endotoxin levels in patients with meningococcal infections. This study
assessed complement activation induced by purified Neisseria meningitidis lipopolysaccharide (Nm-LPS), native outer membrane vesicles (nOMVs), LPS-depleted outer membrane vesicles (dOMVs), wild-type meningococci, and an
LPS-free mutant (lpxA−) from the same strain (44/76) in whole blood anticoagulated with the recombinant hirudin analogue. Complement activation products
(C1rs-C1 inhibitor complexes, C4d, C3bBbP, and terminal SC5b-9 complex) were measured by double-antibody EIAs. Nm-LPS was a weak complement activator. Complement activation increased with preparations containing nOMVs, dOMVs, and wild-type
bacteria at constant LPS concentrations. With the same protein concentration, complement activation induced by nOMVs, dOMVs,
and the LPS-free mutant was equal. The massive complement activation observed in patients with fulminant meningococcal septicemia
is, presumably, an indirect effect of the massive endotoxemia. Outer membrane proteins may be more potent complement activators
than meningococcal LPSs

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