Comparison of serum KL-6 versus bronchoalveolar lavage neutrophilia for the diagnosis of bronchiolitis obliterans in lung transplantation.

BACKGROUND: Bronchiolitis obliterans syndrome (BOS) is a life-threatening complication after lung transplantation that is characterized by progressive fibrosis in the small airways. However, little is known about sensitive markers for detecting BOS. Our study compared the clinical utility of serum KL-6 level, a marker for pulmonary fibrosis, with that of neutrophilia in bronchoalveolar lavage fluid (BALF) for detecting BOS.

METHODS: Levels of serum KL-6 were evaluated in 152 samples from 53 lung transplant recipients (BOS, 15; non-BOS, 38) and in 27 samples from age- and sex-matched healthy individuals. Pulmonary function tests, arterial blood gas analysis, and BALF cell differentials were simultaneously evaluated.

RESULTS: Serum KL-6 levels were significantly increased in the BOS group compared with the non-BOS group and the healthy individuals (p < 0.0001). Receiver operating characteristic curve analysis for detecting BOS showed the largest area under the curve for KL-6 compared with lactate dehydrogenase, C-reactive protein, or neutrophils percentage in BALF. Serum KL-6 correlated with the decline in forced expiratory volume in 1 second (FEV(1)) from post-lung transplant baseline (r = 0.43; p = 0.0001).

CONCLUSIONS: Serum KL-6 levels are increased and correlate with the decline from baseline in FEV(1) in lung transplant recipients. The diagnostic accuracy of serum KL-6 level is better than that of BALF neutrophilia for detecting BOS.