Therefore, in the present study, we evaluated the relationships between KCNJ2 expression and the clinical characteristics of IPF by measuring KCNJ2 protein and mRNA levels in fibroblasts and bronchoalveolar lavage (BAL) fluid from normal controls (NC), patients with IPF, and patients with other interstitial lung diseases, including nonspecific interstitial pneumonia (NSIP), hypersensitivity pneumonitis (HP), and sarcoidosis. The gene discussed is KCNJ2; the disease is hypersensitivity pneumonitis.