OBJECTIVE: To assess the changes in Krebs von den Lungen-6 (KL-6) levels pre- and post-lung transplantation for interstitial lung disease and to determine the connection between changes in KL-6 levels and chronic lung allograft dysfunction. METHODS: Eighty-two lung transplantation procedures were performed in interstitial lung disease patients between January 2008 and December 2019. We compared changes in KL-6 levels before and after transplantation in two groups: unilateral and bilateral lung transplant groups. Additionally, KL-6 levels just before or at the onset of chronic lung allograft dysfunction were compared to the lowest post-transplant levels. RESULTS: In total, 28 female and 49 male patients (median age: 54 years
range 22-64
42 and 35 patients underwent unilateral and bilateral lung transplantations, respectively) were enrolled. The post-transplant observation period ranged from 8 to 163 (median: 64.2) months. KL-6 levels decreased in 76 patients (98.7%). Notably, the KL-6 level was lower in the bilateral lung transplantation group than in the unilateral lung transplantation group. Moreover, KL-6 levels were higher just before or at the onset of chronic lung allograft dysfunction than the lowest post-transplant levels. These levels were significantly higher than the highest post-transplant levels observed in the non-chronic lung allograft dysfunction group. CONCLUSIONS: Our findings suggest that KL-6 levels decrease in interstitial lung disease patients following lung transplantation, with a greater reduction in KL-6 levels observed in bilateral lung transplantation compared to unilateral lung transplantation. Elevated serum KL-6 levels were associated with chronic lung allograft dysfunction, highlighting its utility as a diagnostic biomarker.