Elevation of cytokeratin 19 fragment in patients with interstitial pneumonia associated with polymyositis/dermatomyositis.

Abstract

Cytokeratin 19 fragment (CK19) levels in serum have been documented as a useful tumor marker for lung cancer. We hypothesize that CK19 may increase in serum in patients with interstitial pneumonia associated with polymyositis/dermatomyositis (PM/DM) and CK19 might be a useful variable to evaluate the activity of lung injury. 1. We measured CK19 in sera in 15 patients diagnosed with PM/DM; 6 had nonspecific interstitial pneumonia (NIP), 4 had acute interstitial pneumonia (AIP), and 5 had no pulmonary involvement. We also measured CK19 in 10 healthy nonsmokers serving as a control group. 2. We evaluated the correlation between CK19 level and individual clinical course in patients with pulmonary involvement associated with PM/DM. CK19 levels in sera of patients with NIP associated with PM/DM were significantly higher versus patients with PM/DM without interstitial pneumonia and healthy nonsmokers. CK19 levels in sera in patients with AIP associated with PM/DM were significantly higher compared with the other groups. CK19 values in sera changed according to the progression or improvement of interstitial pneumonia. Immunohistochemical studies using pulmonary tissues obtained at autopsy from patients with AIP associated with PM/DM revealed that the hyaline membrane was mostly stained by anti-human cytokeratin 19 monoclonal antibody as well as the strong positivity of proliferating type II pneumocytes. These results suggest that the measurement of CK19 was a useful variable to evaluate the activity of lung injury in interstitial pneumonia associated with PM/DM.