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Polymorphonuclear leukocyte function during otitis media
Insights
Polymorphonuclear leukocyte (PMN) function is often impaired in children with otitis media, particularly when caused by specific bacteria. This dysfunction may contribute to persistent middle ear infections.
Area of Science:
- Immunology
- Otolaryngology
- Microbiology
Background:
- Otitis media (OM), a common childhood infection, involves middle ear inflammation.
- Polymorphonuclear leukocytes (PMNs) are critical immune cells for fighting bacterial infections.
Purpose of the Study:
- To evaluate polymorphonuclear leukocyte (PMN) function in children with serous (SOM) and mucoid otitis media (MOM).
- To investigate PMN function in an experimental model of acute purulent otitis media caused by Streptococcus pneumoniae in chinchillas.
Main Methods:
- Assessed peripheral blood PMN chemotactic, bactericidal, and chemiluminescence activity in children with OM.
- Induced acute purulent otitis media in chinchillas using Streptococcus pneumoniae and monitored PMN chemotactic activity.
Main Results:
- 18% of children with SOM or MOM exhibited depressed PMN chemotactic activity.
- Children with Hemophilus influenzae in middle ear effusions were more likely to have depressed PMN chemotactic activity.
- Chinchillas with pneumococcal otitis media showed significantly depressed PMN chemotactic activity compared to controls.
Conclusions:
- Bacterial components, possibly capsular polysaccharides from H. influenzae and S. pneumoniae, may impair PMN function.
- Impaired PMN response could lead to delayed bacterial killing and persistent middle ear effusions in otitis media.
Abstract:
Polymorphonuclear leukocyte (PMN) function was evaluated in children with serous (SOM) and mucoid otitis media (MOM) and in an experimental model of acute purulent otitis media due to Streptococcus pneumoniae using chinchillas. Twenty-three of 100 children with SOM or MOM had depressed peripheral blood PMN chemotactic, bactericidal or chemiluminescence activity. Depressed PMN chemotactic activity was observed in 17(18%) of 97 children. Children whose middle ear effusions cultured Hemophilus influenzae were more than twice as likely to have depressed PMN chemotactic activity as children whose effusions were sterile. Depressed PMN bactericidal activity was observed in seven (23%) of 30 children, and depressed PMN chemiluminescence activity was found in three (16%) of 19 children. Combined chemotactic and bactericidal dysfunction was observed in four (13%) of 30 children. All seven of the chinchillas with pneumococcal otitis media showed significantly depressed PMN chemotactic activity during the first week after inoculation, while only two of ten uninfected control chinchillas showed the same degree of chemotactic depression (P = .002). The association of H. influenzae and S. pneumoniae with depressed PMN function suggested that bacterial components of these microbes might have functional similarities. Both bacteria are surrounded by capsular polysaccharides which are known to persist in mammalian tissues for an extended period. It is possible that these or other components of H. influenzae and S. pneumoniae, or even host factors generated during middle ear infection and inflammation, impair the PMN response to middle ear infection resulting in delayed bacterial killing and persistent middle ear effusion.