[The expression and clinical role of KL-6 in serum and BALF of patients with different diffuse interstitial lung diseases].

OBJECTIVE: To detect the levels of KL-6 in the serum and the bronchoalveolar lavage fluid (BALF) of patients with different type of diffuse interstitial lung diseases(DILD), and to analyze its correlation with pulmonary function, pulmonary HRCT scores and other parameters.

METHOD: Seventy-three patients with DILD were enrolled, including 34 patients with idiopathic pulmonary fibrosis (IPF), 10 patients with stage Ⅰ sarcoidosis(SAR Ⅰ), 15 patients with hypersensitivity pneumonia (HP), 14 patients with connective tissue diseases (CTD). Enzyme-linked immune sorbent assay (ELISA) was used to detect the levels of KL-6 in the serum and the BALF of these patients.

RESULTS: In the IPF group, FVC predicted percentage and DLCO predicted percentage were significantly lower than those of the SAR Ⅰ group[(70±14)% vs (82±6)%, (49±13)% vs(81±6)%, P<0.05], but were no different compared to the CTD-ILD group(P>0.05). In the IPF group, the percentage of neutrophils in BALF was higher than that of the SAR Ⅰ group[(9±7)% vs (6±4)%, P<0.05]], and the percentage of lymphocytes and CD4/CD8 ratio in BALF were lower than those of the SAR Ⅰ group[(12±7)% vs (23±13)%, (1.5±0.8) vs(4.0±5.1), P<0.05]. In the IPF group, the level of KL-6 in serum was higher than that of the SAR Ⅰ and the HP group[(858±516)U/ml vs (339±168)U/ml, (553±287)U/ml, P<0.05], but was no different compared to the CTD-ILD group (P>0.05). In the CTD-ILD group, the level of KL-6 in serum was higher than that of the SAR Ⅰ [(687±350) U/ml vs (339±168)U/ml, P<0.05]]. In the IPF group, the level of KL-6 in BALF was (437±252)U/ml, and was higher than that of other 3 groups(P<0.05). In the IPF group, the level of serum KL-6 was negatively correlated with FVC and DLCO(r=-0.46, -0.58, P<0.01), the level of serum KL-6 was positively correlated with pulmonary HRCT reticular pattern and honeycombing scores(r=0.62, 0.41, P<0.05).

CONCLUSIONS: In patients with IPF, the levels of KL-6 in serum and BALF were increased and the level of KL-6 in serum was correlated with FVC, DLCO and pulmonary HRCT reticular pattern and honeycombing scores.KL-6 may be a marker for the diagnosis of IPF.