Related Experiment Videos
The effects of systemic immunization of pulmonary clearance of Pseudomonas aeruginosa
Abstract:
Systemic immunization with gram-negative organisms enhances the subsequent pulmonary clearance of these organisms. We studied the early time course of this phenomenon and related it to the time of appearance of polymorphonuclear leukocytes (PMN) and anti-Pseudomonas antibody in bronchoalveolar lavage (BAL). Mice were immunized intraperitoneally twice, separated by 1 wk, with 10(8) formalin-treated Pseudomonas aeruginosa. Two weeks later, they received an intrabronchial inoculum of 2.9 X 10(6) or 4.6 X 10(7) Pseudomonas organisms. Two, 4, and 6 h later, clearance and total PMN and anti-Pseudomonas antibody in the BAL were assessed. Clearance was enhanced in immunized mice at the lower inoculum. At the higher inoculum, bacteria were growing in lungs of both groups, although they were inhibited in immunized mice. Total PMN in the BAL increased progressively in both groups of mice, but net recruitment was diminished with the high inoculum. There were significant differences in the PMN in the BAL between control and immunized mice with high inoculum. Anti-Pseudomonas IgG first appeared in the BAL at 2 h, anti-Pseudomonas IgM at 6 h. These data suggest that anti-Pseudomonas IgG is an effective early pulmonary opsonin. Further, with high inoculums, immunization may aid pulmonary defenses by diminishing the magnitude of the decrement of PMN in the lung.
Insights
Systemic immunization improves lung clearance of Pseudomonas aeruginosa in mice. Early anti-Pseudomonas IgG in bronchoalveolar lavage (BAL) acts as an opsonin, enhancing bacterial clearance and modulating polymorphonuclear leukocyte (PMN) response.
Area of Science:
- Immunology
- Microbiology
- Pulmonary Medicine
Background:
- Systemic immunization with gram-negative bacteria enhances pulmonary clearance.
- The early time course of this phenomenon and its relation to immune mediators in bronchoalveolar lavage (BAL) require further investigation.
Purpose of the Study:
- To investigate the early time course of enhanced pulmonary clearance following immunization.
- To correlate bacterial clearance with the appearance of polymorphonuclear leukocytes (PMN) and anti-Pseudomonas antibody in BAL.
Main Methods:
- Mice were immunized with formalin-treated Pseudomonas aeruginosa.
- Intrabronchial challenge with Pseudomonas organisms was performed.
- Bacterial clearance, PMN counts, and anti-Pseudomonas antibody levels in BAL were assessed at 2, 4, and 6 hours post-challenge.
Main Results:
- Immunization enhanced bacterial clearance at a lower inoculum.
- At a higher inoculum, immunization inhibited bacterial growth despite continued bacterial presence.
- Anti-Pseudomonas IgG appeared in BAL at 2 hours, and IgM at 6 hours, suggesting IgG's role as an early opsonin.
- PMN recruitment was diminished with high inoculums, but differences were noted between control and immunized mice.
Conclusions:
- Anti-Pseudomonas IgG functions as an effective early pulmonary opsonin.
- Immunization aids pulmonary defenses by mitigating PMN reduction during high-level bacterial challenge.