Is KL-6 a serum indicator of early pulmonary fibrosis in childhood cancer patients?

Krebs von den Lungen-6 as a biomarker for disease severity assessment in interstitial lung disease: a comprehensive review

Aim: Interstitial lung diseases (ILD) are a group of lung disorders characterized by interstitial lung thickening. Krebs von den Lungen-6 (KL-6) is a molecule that is predominantly expressed by damaged alveolar type II cells and it has been proposed as a potential biomarker of different ILD. Materials & methods: A growing literature about KL-6 has been reviewed and selected to evaluate its role in the clinical management of ILD to predict disease diagnosis, activity, prognosis and treatment response. Results: KL-6 concentrations have been evaluated in fibrotic and granulomatous lung diseases and it was demonstrated to be a biomarker of disease severity useful for clinical follow-up of ILD patients. KL-6 levels differentiated between fibrotic ILD, such as idiopathic pulmonary fibrosis and chronic hypersensitivity pneumonitis, and nonfibrotic lung disorders, including sarcoidosis and pulmonary alveolar proteinosis. Conclusion: KL-6 is predictive biomarker useful in the clinical management of ILD patients, in particular in patients with severe fibrotic lung disorders.

Serum KL-6 and surfactant protein D in children with 2009 pandemic H1N1 influenza infection

BACKGROUND

A global pandemic influenza A (H1N1) outbreak occurred in 2009. Rapid progress of respiratory distress is one of the characteristic features of pandemic influenza A (H1N1) infection. The physiologic mechanism causing hypoxia in pandemic influenza A (H1N1) infection, however, has not been elucidated.

METHODS

The serum levels of KL-6 and surfactant protein D (SP-D) were evaluated in 21 cases of pandemic influenza A (H1N1) infection associated with chest radiographic abnormality in order to estimate alveolar involvement. The clinical features were also analyzed.

RESULTS

All of the patients had high fever, and rapidly progressed to respiratory distress within several days of disease onset. Despite mild radiographic abnormality in these patients, dyspnea was severe and they had low blood oxygen saturation levels. Many of the patients had a history of allergic diseases including asthma. Serum KL-6 and SP-D levels on admission were 191 ± 69 U/mL and 32.6 ± 18.9 ng/mL, respectively. These two levels were still below the upper normal limit 1 week later. There were no clear relationships between specific clinical symptoms and KL-6 or SP-D levels. All patients were treated with oseltamivir and/or zanamivir, and improved without mechanical ventilation management.

CONCLUSION

KL-6 and SP-D elevation were not significant in pandemic influenza A (H1N1) infection associated with chest radiographic abnormality. In pandemic influenza A (H1N1) infection, alveolar involvement was estimated to be little, and severe respiratory distress was probably caused by obstruction of peripheral bronchi.

The role of serum KL-6 measurement in common pediatric respiratory infections

KL-6 is a useful marker for interstitial pneumonia of various origins. However, the role of KL-6 in common pediatric respiratory infections is largely unknown. In order to determine whether the KL-6 level is elevated during respiratory infection, and whether KL-6 is a useful biomarker for the disease activity, we evaluated serum KL-6 levels in 132 children with various respiratory infections. KL-6 levels were significantly higher in patients with measles, influenza, or respiratory syncytial virus infection than in the control subjects. On the other hand, KL-6 levels in patients with bacterial infections such as mycoplasma, chlamydia, or pertussis were comparable to the control values. In patients with viral infections, high KL-6 levels, as defined by the mean plus 2 standard deviations of the control group, significantly correlated with low SpO(2) or days of O(2) administration, but did not correlate with C-reactive protein or white blood cell counts. These results indicate that measurement of serum KL-6 levels is helpful for the management of common pediatric respiratory infections.