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Surfactant protein D: subcellular localization in nonciliated bronchiolar epithelial cells
1Department of Pathology, Jewish Hospital, Washington University Medical Center, St. Louis, Missouri 63110.
The American Journal of Physiology
|July 1, 1992
Summary
Surfactant protein D (SP-D) is found in Clara cells within the small airways, not just type II pneumocytes. This suggests SP-D plays a role in lung defense and surfactant metabolism.
Area of Science:
- Pulmonary Biology
- Cell Biology
- Immunology
Background:
- Surfactant protein D (SP-D) is a collagenous carbohydrate-binding protein.
- Initially identified as a product of type II pneumocytes in the lungs.
Purpose of the Study:
- To investigate the cellular distribution and subcellular localization of SP-D in rat small airways.
- To determine if SP-D is produced by cells other than type II pneumocytes.
Main Methods:
- Immunoperoxidase staining of lung tissue.
- Immunogold-labeling techniques using antibodies against SP-D.
- Electron microscopy to examine subcellular localization in nonciliated bronchiolar cells (Clara cells).
Main Results:
- SP-D was detected in the cytoplasm and apical secretory granules of Clara cells in small airways.
- Labeling was most prominent in distal membranous bronchioles, decreasing proximally.
- No SP-D labeling was found in large airways or trachea.
Conclusions:
- SP-D is a secretory product of nonciliated bronchiolar Clara cells.
- Clara cell-derived SP-D is likely a component of the bronchiolar lining material.
- SP-D may contribute to surfactant metabolism and host defense in small airways.