ABERRANT APPEARANCE OF LUNG SURFACTANT PROTEIN-A IN SERA OF PATIENTS WITH IDIOPATHIC PULMONARY FIBROSIS AND ITS CLINICAL-SIGNIFICANCE

Pulmonary surfactant protein A (SP-A) is known to be a major phospholi pid-associated glycoprotein in pulmonary surfactant, which is specific to the lung. In this study, the SP-A concentrations in sera of patien ts with various lung diseases were determined using an enzyme-linked i mmunosorbent assay. Patients with idiopathic pulmonary fibrosis (IPF) and pulmonary alveolar proteinosis (PAP) exhibited prominently high co ncentrations of serum SP-A compared to those of other lung diseases an d healthy volunteers, although there were significant increases in ser um SP-A concentrations in patients with pulmonary tuberculosis, chroni c pulmonary emphysema, diffuse panbronchiolitis and bacterial pneumoni a compared to those of healthy volunteers. Successive measurement in 2 patients with IPF showed that serum SP-A levels reflect the disease a ctivity of IPF. In patients with IPF, serum SP-A concentrations were s ignificantly correlated with those of serum lactate dehydrogenase, whe reas there were no significant correlations of serum SP-A concentratio ns with erythrocyte sedimentation rate, arterial oxygen saturation, vi tal capacity and carbon monoxide diffusing capacity. Determination of serum SP-A will contribute to diagnosing IPF and PAP, and may reflect the disease activity of IPF.