ObjectiveTo detect the levels of Krebs von den lungen 6 (KL-6) in bronchoalveolar lavage fluid (BALF) and serum of patients with idiopathic pulmonary fibrosis (IPF),and explore its clinical significance. MethodsThirty-four patients with IPF and 10 patients with sarcoidosis in Ⅰ period were recruited in the study. ELISA was used to detect the level of KL-6 in BALF and serum. ResultsIn the IPF group,the forced vital capacity as percentage of predicted value (FVC% pred) and diffusion capacity for carbon monoxide as percentage of predicted value (DLCO %pred) were both significantly lower than those of the sarcoidosis group[(69.51±13.65)% vs. (82.06±5.84)%,(48.58±12.73)% vs. (81.47±6.39)%,P<0.01]. In the BALF of IPF group,the percentage of neutrophils was higher[(8.91±6.79)% vs. (5.50±3.60)%,P<0.05],and the percentages of lymphocytes and CD4/CD8 ratio were lower than those of the sarcoidosis group[(11.71±6.64)% vs. (23.30±12.68)%,(1.46±0.83) vs. (4.01±5.10),P<0.05]. In the IPF group,the level of KL-6 in the BALF and serum was higher than that of the arcoidosis group[(437.43±251.70) U/mL vs. (221.59±127.41) U/mL,(857.81±515.53) U/mL vs. (338.67±168.13) U/mL,P<0.001]. There was obvious correlation between the level of serum KL-6 with FVC%pred and DLCO%pred in the IPF group (r=-0.46,r=-0.58,P<0.05). ConclusionsThe level of KL-6 in BALF and serum is elevated in patients with IPF. There is obvious correlation between the level of serum KL-6 with FVC%pred and DLCO%pred in IPF patients. KL-6 may be an indicator of IPF in clinical diagnose.