Detection of interstitial pneumonitis in patients with rheumatoid arthritis by measuring circulating levels of KL-6, a human MUC1 mucin

Lung. 1997;175(6):379-85. doi: 10.1007/pl00007584.


In rheumatoid arthritis (RA), interstitial-pneumonitis is one of the major extraarticular complications that worsens a patient's prognosis. KL-6, a human MUC1 mucin, has been reported to be a sensitive serum marker for activity of interstitial pneumonitis. We investigated the clinical significance of serum KL-6 level in patients with RA. Serum levels of KL-6 and RA-associated inflammatory markers were evaluated in 177 RA patients. The diagnosis of active interstitial pneumonitis was made by clinical symptoms, pulmonary function tests, chest X-ray film, and high resolution CT. Serum KL-6 was increased in 8 of 9 (88.9%) RA patients with active interstitial pneumonitis but in only 1 of 168 (0.6%) RA patients without active interstitial pneumonitis. No significant correlation was found between KL-6 level and conventional clinical parameters. In RA, abnormal elevation of serum KL-6 strongly indicates the complication of active interstitial pneumonitis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Antigens / blood*
  • Antigens, Neoplasm
  • Arthritis, Rheumatoid / blood
  • Arthritis, Rheumatoid / diagnosis*
  • Biomarkers / blood
  • Female
  • Glycoproteins / blood*
  • Humans
  • Lung Diseases, Interstitial / blood
  • Lung Diseases, Interstitial / diagnosis*
  • Male
  • Middle Aged
  • Mucin-1
  • Mucins
  • Predictive Value of Tests


  • Antigens
  • Antigens, Neoplasm
  • Biomarkers
  • Glycoproteins
  • MUC1 protein, human
  • Mucin-1
  • Mucins