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1991
Journal Article
Titel
Surfactant protein A in human pleural fluids.
Alternative
Surfactant Protein A in menschlicher Pleuralflüssigkeit
Abstract
There have been repeated reports suggesting the existence of surfactant systems outside the bronchoalveolar tree. Hills et al. described surface active phospholipids on the canine pleura and speculated on their role as boundary lubricants. However, the presence of phospholipids is not a finding specific to surfactant material. We investigated human pleural transudates in the absence of local pleural disease (n=8) and pleural exudates due to local inflammation or malignant disease (n=10). Surfactant protein A (SP-A) ooncentrations were measured using a monoclonal ELISA-assay specific to human SP-A (Teijin Ltd., Japan). Further, more, pleural biopsy material obtained from thoracoscopy and thoracic surgical procedures were investigated by transmission and scanning electron microscopy (TEM and SEM) for evidence of local surfactant synthesis and secretion. Additionally, we performed imuno histochemicaJ studies using an SP-A specific antibody. mean SP-A level in transudates was 695 ng/ml (ra nge 280-1750). In exudates it was 373 ng/ml (range 150- 600). These results suggest that SP-A in pleural fluids does not originate from a pleuropulmonary leakage. Lower SP-A values in exudates may possibly indicate impaired surfactant production in the diseased pleura. TEM of the pleural biopsies demonstrated surfactant-like lamellar bodies in pleural mesothelial cells. SEM showed surfactant-like material on the pleural mesothe lial surface. We conclude that we have found evidence of a locally synthesized surfactant material on the human pleura. Pleural surfactants could serve as boundary lubricants to reduce friction in the Pleural space throughout the ventilatory cycle. Additionally, they perhaps support local defence mechanisms analogous to known surfactant functions in the alveolar milieu.