KL-6, surfactant protein A and D in bronchoalveolar lavage fluid from patients with pulmonary sarcoidosis.

BACKGROUND: KL-6, and surfactant protein A (SP-A) and surfactant protein D (SP-D) derived from alveolar type II cells and/or bronchiolar epithelial cells have been reported to be useful markers for interstitial lung diseases. OBJECTIVE: The aim of this study was to measure the levels of these molecules in bronchoalveolar lavage fluid (BALF) from patients with pulmonary sarcoidosis to investigate their relationship with other markers of inflammatory activity. METHODS: We measured KL-6, SP-A and SP-D levels in BALF from patients with pulmonary sarcoidosis using an ELISA. RESULTS: KL-6 and SP-D, but not SP-A levels were significantly increased in pulmonary sarcoidosis compared with controls. KL-6, SP-A and SP-D levels were significantly correlated with each other. KL-6 and SP-D levels were relatively and significantly correlated with the percentage of lymphocytes in BALF. KL-6, SP-D, but not SP-A levels were significantly correlated with the concentration of albumin in BALF. There was no significant correlation between KL-6, SP-A, or SP-D levels and chest X-ray findings, angiotensin-converting enzyme levels, or CD4/CD8 ratio in BALF. CONCLUSIONS: We conclude that KL-6 and SP-D levels in BALF were increased in pulmonary sarcoidosis. Since these markers are specifically derived from epithelial cells, it is considered that KL-6 and SP-D levels are reflecting damage or release of these markers from epithelial cells due to the inflammatory response.