Surfactant Protein B

Surfactant protein B (SP-B) is one of the core components of pulmonary surfactant, mainly secreted by type II alveolar cells. SP-B can promote the formation of stable phospholipid monolayers on the surface of alveoli, thereby reducing alveolar surface tension and preventing end-expiratory alveolar collapse, which plays an important role in alveolar structure stability and respiratory function maintaining. In clinical practice, SP-B is mainly used as a specific biomarker for lung adenocarcinoma, which is almost not expressed in lung squamous cell carcinoma, large cell lung cancer, and small cell lung cancer, but it has low sensitivity and limited value when used alone. Therefore, SP-B is often used in combination with Napsin A and TTF-1 for the differential diagnosis of lung adenocarcinoma (+) and lung squamous cell carcinoma (-), and the addition of CK7 and CK20 can distinguish between lung primary adenocarcinoma and lung metastatic adenocarcinoma. In addition, some scholars pointed out that the expression rate of SP-B is down-regulated with the decreased degree of tumor differentiation, so its high expression may be related to patient good prognosis.