IgG antibody levels in the sinus, ear, and airway in a rabbit model of sinusitis with Bacteroides.
OBJECTIVE
To evaluate distribution of IgG antibodies (Ab) in the airway, ear, and sinuses in association with inflammatory changes in a rabbit sinusitis model.


METHODS
We measured IgG Ab and lactate dehydrogenase levels in solutions from sinus, airway, and middle ear lavage and in serum, and determined interferon y messenger RNA expression in sinus and ear mucosa at 1, 2, 3, and 4 weeks after inoculation with Bacteroides fragilis.


METHODS
Six rabbits at each time point; controls were untreated (n=5) and sham-operated rabbits at 2 and 4 weeks (n=4-5).


METHODS
Bacteroides fragilis was inoculated into the left maxillary sinus with ostium closed.


RESULTS
IgG Ab was undetectable in all controls. IgG Ab (>50 microg/g protein) was present at 2, 3, and 4 weeks in most bilateral sinus lavage samples and in 2 of 6, 5 of 6, and 6 of 10 ear lavage samples at 2, 3, and 4 weeks, respectively, following inoculation. Inflammatory changes (histological and lactate dehydrogenase) were much greater in the inflamed sinus. IgG Ab (>50 microg/g protein) was also detected in most bronchoalveolar lavage samples after 2 weeks. Interferon gamma mRNA was undetectable in all untreated and most sham-operated controls but was detected in the bilateral sinus mucosa at 1 to 2 weeks, and remained detectable up to 4 weeks in most rabbits. Serum IgG Ab levels positively correlated with those in lavage samples, with highest correlation with right sinus lavage IgG Ab levels (r=0.56, P<.001).


CONCLUSIONS
IgG Ab levels in the upper airway mucosa likely increase within 2 weeks following bacterial inoculation as a part of mucosal immune responses independent of tissue necrosis.
Jyonouchi
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Department of Pediatrics, School of Medicine, University of Minnesota, Minneapolis 55455, USA. jyono001@jyono001.email.umn.edu
Sun
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Kennedy
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Kajander
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Rimell
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D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood / Q000235:genetics; D001442:Bacteroides Infections / Q000201:enzymology / Q000276:immunology*; D001441:Bacteroides fragilis / Q000276:immunology*; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D004195:Disease Models, Animal; D004432:Ear, Middle / Q000276:immunology; D018928:Immunity, Mucosal; D007074:Immunoglobulin G / Q000097:blood / Q000302:isolation & purification*; D007770:L-Lactate Dehydrogenase / Q000097:blood / Q000378:metabolism*; D008297:Male; D008443:Maxillary Sinus / Q000276:immunology; D012333:RNA, Messenger; D011817:Rabbits; D012852:Sinusitis / Q000201:enzymology / Q000276:immunology* / Q000382:microbiology
D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D012333:RNA, Messenger; D007770:L-Lactate Dehydrogenase