Related Experiment Videos
Early pulmonary granulocyte recruitment in response to Streptococcus pneumoniae
Abstract:
Although polymorphonuclear leukocytes (PMN) are a conspicuous histologic feature of clinical and experimental pneumococcal pneumonia, neither the mechanism nor the magnitude of recruitment of these cells to the lung following lesser pneumococcal challenge is known. We have, therefore, investigated the early process of recruitment of PMN to alveolar spaces after pulmonary inoculation of Streptococcus pneumoniae in doses less than those causing pneumonia. We injected Balb/c mice with water and varying inoculums of pneumococci via an endobronchial catheter. Bronchoalveolar lavage (BAL) was performed on the inoculated lung at 0, 2, or 4 h after injection. Cellular response was measured and chemotactic activity was assayed on BAL supernatants at each time interval using the migration of human PMN through 3-micron filters in modified Boyden chambers by the leading front techniques. The BAL of normal and control animals (inoculum of sterile water only used for the control animals) yielded 5.03 +/- 1.51 X 10(2) and 0.17 +/- 0.04 X 10(5) PMN, respectively. The PMN recruitment at 4 h as a function of pneumococcal inoculum was described by the following equation: log PMN = 0.751 log Pn + 1.119 (r2 = 0.82, p less than 0.001). The PMN were, therefore, recruited in a dose-dependent manner. That recruitment may be caused by chemotactic substance(s) was suggested by the significant correlation between the PMN response and the distance of in vitro migration: log PMN = 0.057 micron + 0.52 (r = 0.77, p less than 0.005). We have defined quantitatively the recruitment of PMN to the lung after pneumococcal challenge.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Polymorphonuclear leukocytes (PMN) are recruited to the lungs in a dose-dependent manner following Streptococcus pneumoniae challenge. This early immune response is mediated by chemotactic substances, quantifying PMN recruitment in pneumococcal pneumonia.
Area of Science:
- Immunology
- Pulmonary Medicine
- Microbiology
Background:
- Polymorphonuclear leukocytes (PMN) are key immune cells in pneumonia.
- The mechanism and extent of PMN recruitment in early pneumococcal lung challenge are not well understood.
Purpose of the Study:
- To investigate the early recruitment process of PMN to the alveolar spaces.
- To quantify PMN recruitment following sub-pneumonic doses of Streptococcus pneumoniae.
Main Methods:
- Balb/c mice were inoculated with varying doses of S. pneumoniae via endobronchial catheter.
- Bronchoalveolar lavage (BAL) was performed at 0, 2, and 4 hours post-inoculation.
- Cellular response and chemotactic activity of BAL supernatants were measured using modified Boyden chambers.
Main Results:
- PMN recruitment to the lung was dose-dependent on the pneumococcal inoculum (log PMN = 0.751 log Pn + 1.119).
- A significant correlation was observed between PMN response and in vitro migration distance, suggesting chemotactic mediation (log PMN = 0.057 micron + 0.52).
- Quantitative data on early PMN recruitment following pneumococcal challenge were established.
Conclusions:
- Early PMN recruitment to the lung in response to Streptococcus pneumoniae is a dose-dependent process.
- Chemotactic factors present in bronchoalveolar lavage fluid play a significant role in PMN migration.
- This study quantitatively defines the early inflammatory response in pneumococcal lung infections.