Related Experiment Videos
Pneumocystis carinii induces an oxidative burst in alveolar macrophages
H A Hidalgo1, R J Helmke, V F German
1Department of Pediatrics, University of Texas Health Science Center, San Antonio 78284-7815.
Abstract:
There is evidence that alveolar macrophages (AM) play a role in the clearing of Pneumocystis carinii from the lungs. To investigate the mechanisms involved in this process, we studied in vitro the induction of an oxidative burst by P. carinii in a cell line of macrophages (NR8383) and AM from normal rats. P. carinii was added to macrophage monolayers (10(6) cells), and the H2O2 produced after 4 h of incubation was measured. Both NR8383 macrophages and normal rat AM produced H2O2 in response to P. carinii cysts and trophozoites isolated from dexamethasone-treated rats, although the amount of H2O2 induced in AM from normal rats was larger. NR8383 macrophages bound and phagocytized both P. carinii cysts and trophozoites and produced increasing amounts of H2O2 as a dose-related response to cysts and trophozoites. Opsonization of P. carinii with normal rat serum increased H2O2 production by both types of macrophages; this enhancement was decreased, but not abolished, when the serum was first depleted of complement by heat treatment. These findings demonstrate that NR8383 macrophages and normal rat AM produce an oxidative burst in response to P. carinii and that this response is enhanced by complement.
Insights
Alveolar macrophages (AM) generate an oxidative burst to clear Pneumocystis carinii. Complement enhances this immune response, crucial for combating lung infections.
Area of Science:
- Immunology
- Cell Biology
- Microbiology
Background:
- Alveolar macrophages (AM) are implicated in clearing Pneumocystis carinii from the lungs.
- Understanding the mechanisms of AM-mediated pathogen clearance is vital for respiratory health.
Purpose of the Study:
- To investigate the in vitro induction of an oxidative burst by Pneumocystis carinii in macrophage cell lines and AM.
- To elucidate the role of complement in enhancing macrophage responses to P. carinii.
Main Methods:
- Incubation of macrophage monolayers (NR8383 cell line and rat AM) with P. carinii (cysts and trophozoites).
- Measurement of hydrogen peroxide (H2O2) production as an indicator of oxidative burst.
- Assessment of P. carinii opsonization with normal rat serum and complement depletion effects.
Main Results:
- Both NR8383 macrophages and rat AM produced H2O2 in response to P. carinii.
- AM from normal rats produced higher levels of H2O2 compared to the NR8383 cell line.
- Opsonization with normal rat serum significantly enhanced H2O2 production, an effect partially dependent on complement.
Conclusions:
- NR8383 macrophages and normal rat AM mount an oxidative burst against P. carinii.
- Complement-mediated opsonization enhances the macrophage oxidative burst response to P. carinii, suggesting a key role in host defense.