Objectives: Surfactant protein (SP) A and D are specific serum markers for interstitial lung diseases including idiopathic pulmonary fibrosis (IPF). The authors evaluated the critical roles of these markers on the prognoses of patients with IPF and the mechanisms of their elevation in sera.
Methodology: The authors evaluated the relationship between prognosis and the serum markers in 82 IPF patients. The protein content and mRNA expression of the markers were evaluated using rats with interstitial pneumonia induced by bleomycin administration.
Results: Higher levels of serum SP-D at the time of the initial visit to the Sapporo Medical University Hospital were associated with poorer prognoses, while SP-A showed no significant affect on survival. Causes of the elevation in sera were due to the acceleration of, not only production in the lungs, leakage into the circulation. The elevation was associated with alveolitis but not fibrosis.
Conclusions: SP-D is a good predictor of the prognosis in patients with IPF.