Tuberc Respir Dis > Accepted Articles
Interstitial Lung Diseases
DOI:    [Accepted]
Published online April 6, 2021.
Role of Krebs von den Lungen-6 (KL-6) in Assessing Hypersensitivity Pneumonitis
Amira Ismail Mostafa, M.D.1  , Ayman Elsayed Salem, M.D.1, Heba Allah Moussa Ahmed, M.D.1, Aml Ibrahim Bayoumi, M.D.1, Radwa M. Abdel Halim, M.D.2, Rasha M. Abdel Samie, M.D.3
1Department of Chest Diseases, Faculty of Medicine, Cairo University, Shiekh Zayed City, Egypt
2Department of Chemical Pathology, Faculty of Medicine, Cairo University, Shiekh Zayed City, Egypt
3Department of Internal Medicine, Faculty of Medicine, Cairo University, Shiekh Zayed City, Egypt
Correspondence:  Amira Ismail Mostafa, Tel: 20-01224977400, 
Received: 9 October 2020   • Revised: 7 March 2021   • Accepted: 5 April 2021
Hypersensitivity pneumonitis (HP) is an increasingly recognized form of diffuse parenchymal lung disease. Krebs von den Lungen-6 (KL-6) is now classified as a human MUC1 mucin protein, and regenerating type II pneumocytes are the primary cellular source of KL-6/MUC1 in the affected lungs of patients with interstitial lung diseases (ILD). Serum KL-6/MUC1 levels have been demonstrated to be useful for the evaluation of various ILD. To determine the role of circulating KL-6 in evaluating the disease activity and management of HP.
An observational cross-sectional study was conducted on 51 patients with HP and 20 healthy controls. Serum KL-6 levels were measured in both groups. Patients were further assessed based on chest high-resolution computed tomography (HRCT), pulmonary function test, 6-minute walk test, echocardiography, bronchioalveolar lavage, and/or transbronchial biopsy. Patients were divided into the fibrotic and non-fibrotic groups according to the HRCT findings.
The median serum KL-6 levels were significantly higher in HP patients as compared to the control group. The median serum KL-6 levels were found to be higher in the non-fibrotic HP group (1,900 IU/mL) as compared to the fibrotic group (1,200 IU/mL). There was a significant inverse correlation between serum KL-6 serum level and the dose of steroids as well as the duration of steroid therapy.
The presence of higher KL-6 levels in the non-fibrotic HP group implies its enhanced production by regenerating pneumocytes in response to alveolar injury. The significant association between serum KL-6 levels and the dose and the duration of steroid therapy emphasizes the significant role of steroids in the stabilization of the disease.
Key Words: Hypersensitivity Pneumonitis, Serum Biomarker, KL-6, Assessment of Severity

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