Abstract
The mechanism of antibody-mediated reduction of Haemophilus influenzae type b (Hib) carriage was studied in the infant rat colonization model. Monoclonal Hib polysaccharide (PS) antibody (MAb) given intranasally or intraperitoneally and human secretory anti-Hib PS IgA given intranasally inhibited colonization by Hib during the entire follow-up period (2-48 h after challenge) but did not affect colonization by Hi, a noncapsulated variant of Hib. F(ab')2 fragments, prepared from the MAb or from human serum anti-Hib IgG reduced Hib colonization as efficiently as the uncleaved molecules. Complement depletion by cobra venom treatment had no effect on the antibody-mediated reduction of Hib colonization. These results indicate that Fc-mediated activities of immunoglobulins are not essential in the reduction of Hib colonization. Instead, antibodies to Hib most likely reduce colonization by a direct effect on growth of the bacteria or their adherence to the nasopharyngeal mucosa.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Antibodies, Bacterial / immunology*
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Antibodies, Monoclonal / chemistry
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Antibodies, Monoclonal / immunology*
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Antibodies, Monoclonal / therapeutic use*
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Complement System Proteins / immunology
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Complement System Proteins / metabolism
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Genetic Variation
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Haemophilus Infections / immunology*
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Haemophilus Infections / microbiology
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Haemophilus Infections / prevention & control*
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Haemophilus influenzae / genetics
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Haemophilus influenzae / growth & development*
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Haemophilus influenzae / immunology*
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Immunoglobulin A / immunology*
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Immunoglobulin A / therapeutic use*
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Immunoglobulin Fab Fragments / immunology
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Immunoglobulin Fab Fragments / therapeutic use
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Immunoglobulin G / chemistry
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Immunoglobulin G / immunology
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Kinetics
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Nasopharynx / immunology
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Nasopharynx / microbiology
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Polysaccharides, Bacterial / immunology*
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Rats
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Rats, Wistar
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Specific Pathogen-Free Organisms
Substances
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Antibodies, Bacterial
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Antibodies, Monoclonal
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Immunoglobulin A
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Immunoglobulin Fab Fragments
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Immunoglobulin G
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Polysaccharides, Bacterial
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Complement System Proteins