PURPOSE: Children's interstitial lung disease (chILD) encompasses a heterogeneous group of rare diffuse lung disorders with varying prognoses. More severe forms include the inborn errors of surfactant metabolism (IESM), such as surfactant protein C (SP-C) and ABCA3 deficiency. In contrast, neuroendocrine cell hyperplasia of infancy (NEHI) is considered a benign form. KL-6, a glycoprotein expressed mainly by activated type 2 pneumocytes, has been shown to be elevated in serum in a variety of interstitial lung diseases in both adults and children. Since alveolar epithelial cell hyperplasia is a common histologic feature of IESM, but not of NEHI, we hypothesized that KL-6 would be elevated in IESM, but not in NEHI.
METHODS: We measured KL-6 levels in the serum of a cohort of 10 healthy control children, 10 children with IESM, (including 4 with SP-C deficiency and 6 with ABCA3 deficiency), and 2 children with NEHI.
RESULTS: The mean (± SEM) serum KL-6 levels were 206 (± 47), 3039 (± 817), and 181 (± 135) U/ml, for the control, IESM, and NEHI groups, respectively. Serum KL-6 levels were significantly elevated in the IESM group when compared to the control group (p<0.01) and the NEHI group (p<0.01). There was no difference in serum KL-6 levels between the control and NEHI groups (p=0.89).
CONCLUSION: Children with IESM have elevated serum KL-6 levels, in contrast to those with NEHI who have normal KL-6 levels.
CLINICAL IMPLICATIONS: Serum KL-6 may be a useful biomarker for distinguishing between severe and benign forms of chILD.
DISCLOSURE: Minh Doan, None.