Increased severity of respiratory infections associated with elevated anti-LPS IgG2 which inhibits serum bactericidal killing


Although specific antibody induced by pathogens or vaccines is a key component of protection against infectious threats, some viruses, such as dengue, induce antibody that enhances the development of infection. In contrast, antibody-dependent enhancement of bacterial infection is largely unrecognized. Here, we demonstrate that in a significant portion of patients with bronchiectasis and Pseudomonas aeruginosa lung infection, antibody can protect the bacterium from complement-mediated killing. Strains that resist antibody-induced, complement-mediated killing produce lipopolysaccharide containing O-antigen. The inhibition of antibody-mediated killing is caused by excess production of O-antigen-specific IgG2 antibodies. Depletion of IgG2 to O-antigen restores the ability of sera to kill strains with long-chain O-antigen. Patients with impaired serum-mediated killing of P. aeruginosa by IgG2 have poorer respiratory function than infected patients who do not produce inhibitory antibody. We suggest that excessive binding of IgG2 to O-antigen shields the bacterium from other antibodies that can induce complement-mediated killing of bacteria. As there is significant sharing of O-antigen structure between different Gram-negative bacteria, this IgG2-mediated impairment of killing may operate in other Gram-negative infections. These findings have marked implications for our understanding of protection generated by natural infection and for the design of vaccines, which should avoid inducing such blocking antibodies.

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Divisions: College of Health & Life Sciences > School of Biosciences
Additional Information: © 2014 Wells et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at
Uncontrolled Keywords: Antibodies, Blocking/blood,Antibody-Dependent Enhancement/immunology,Blood Bactericidal Activity/immunology,Bronchiectasis/blood,Complement System Proteins/immunology,Humans,Immunoglobulin G/blood,O Antigens/immunology,Pseudomonas Infections/blood,Pseudomonas aeruginosa/immunology,Respiratory Tract Infections/blood
Publication ISSN: 1540-9538
Last Modified: 08 Jul 2024 08:09
Date Deposited: 18 Jan 2022 14:15
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Related URLs: https://rupress ... tory-infections (Publisher URL)
PURE Output Type: Article
Published Date: 2014-08-11
Authors: Wells, Timothy J
Whitters, Deborah
Sevastsyanovich, Yanina R
Heath, Jennifer N
Pravin, John
Goodall, Margaret
Browning, Douglas F (ORCID Profile 0000-0003-4672-3514)
O'Shea, Matthew K
Cranston, Amy
De Soyza, Anthony
Cunningham, Adam F
MacLennan, Calman A
Henderson, Ian R
Stockley, Robert A


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