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Inflammatory cell distribution within and along asthmatic airways
K J Haley1, M E Sunday, B R Wiggs
1Pulmonary and Critical Care Division, Departments of Medicine and Departments of Surgery and Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
American Journal of Respiratory and Critical Care Medicine
|August 12, 1998
Summary
Severe asthma involves distinct inflammatory cell distribution in small airways, with higher densities in the outer airway wall. This differs from cystic fibrosis, potentially explaining peripheral airway obstruction in asthma.
Area of Science:
- Pulmonary Medicine
- Immunology
- Pathology
Background:
- Asthmatic airways exhibit infiltration by inflammatory cells and release of mediators.
- Understanding the precise distribution of these cells is crucial for elucidating asthma pathophysiology.
Purpose of the Study:
- To compare the distribution of CD45-positive leukocytes and eosinophils in lung tissue from patients with severe asthma versus cystic fibrosis.
- To investigate regional variations in inflammatory cell density within the airway wall.
Main Methods:
- Morphometric analysis of lung tissue from five severe asthma and five cystic fibrosis patients.
- Partitioning of the airway wall into inner (subepithelial) and outer (parenchymal) regions.
- Quantification of CD45-positive cells and eosinophils in large and small airways.
Main Results:
- Both large and small airways in asthma and cystic fibrosis showed higher CD45-positive cell and eosinophil density in the inner airway region compared to outer.
- In small airways of asthmatic lungs, there was a significantly greater density of CD45-positive cells and eosinophils in the outer airway wall region compared to the inner region.
- These specific regional variations in small airways were not observed in cystic fibrosis lungs.
Conclusions:
- Severe asthma is characterized by unique regional variations in inflammatory cell distribution within the airway wall, particularly in small airways.
- The increased density of inflammatory cells in the outer wall of small airways in asthma may contribute to peripheral airway obstruction.
- These findings highlight differences in airway inflammation between severe asthma and cystic fibrosis.