MUC1 and cryptogenic organizing pneumonia: In the aforementioned studies, serum KL-6 levels were increased in patients with DILD with diffuse alveolar damage, chronic interstitial pneumonia, or acute interstitial pneumonia patterns, but not in those with bronchiolitis obliterans organizing pneumonia, eosinophilic pneumonia, or hypersensitivity pneumonitis patterns18, 30.