ABSTRACT
I. Introduction 383
II. General Aspects of Airway Surfactant 384
A. Functions 384
B. Morphology 386
C. Composition 386
III. Surfactant Alterations in Asthma 387
IV. Modulation of Immune Cells in Allergic Inflammation 389
A. Allergen Binding 390
B. Dendritic Cells 390
C. Lymphocytes 390
D. Eosinophils 391
V. Therapeutic Potential and Clinical Aspects 391
VI. Conclusions 392
References 393
I. Introduction
Pulmonary surfactant reduces the surface tension at the air-liquid interface in the
entire lung. This surfactant lining layer, which is present in the alveoli and the
airways, is composed of phospholipids, mainly dipalmitoylphosphatidylcho-
line (DPPC) and surfactant-specific proteins. Reduction of surface tension at the
air-liquid interface prevents alveolar collapse at end expiration, contributes to
airway stability and openness, and thus allows for cyclic ventilation of the
lungs. This basic functional principle of pulmonary surfactant was invented
more than 70 years ago. The pathogenetic relevance of surfactant was initially
recognized in infant respiratory distress syndrome as a quantitative surfactant
deficiency (1), but today biochemical and biophysical surfactant abnormalities
have been reported in various lung diseases, such as acute respiratory distress
syndrome, pneumonia, cardiogenic lung edema (2), following lung transplan-
tation (3), as well as in patients with cystic fibrosis (4), and asthma (5).
