KL-6 as a novel serum marker for interstitial pneumonia associated with collagen diseases

J Rheumatol. 2000 May;27(5):1164-70.


Objective: To investigate the diagnostic value of the serum concentrations of KL-6, a mucinous glycoprotein expressed on type II pneumocytes, for interstitial pneumonia (IP) in various collagen diseases.

Methods: Serum KL-6 levels were measured by ELISA.

Results: The mean values and the positive rates of serum KL-6 levels for patients with rheumatoid arthritis, systemic sclerosis, or polymyositis/dermatomyositis with IP were significantly higher than those without IP. Sensitivity, specificity, positive and negative predictive values of serum KL-6 level for IP associated with collagen diseases were 60.7, 98.9, 97.4, and 77.1%, respectively. The mean serum KL-6 level of patients with active IP was significantly (p = 0.0001) higher than that of patients with inactive IP. Serum KL-6 levels increased with the deterioration of IP, while the successful treatment of IP resulted in a significant decrease of these levels.

Conclusion: Serum KL-6 concentration levels are a useful marker for diagnosis and evaluation of the disease activity of IP associated with collagen diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antigens / blood*
  • Antigens, Neoplasm
  • Biomarkers / blood
  • C-Reactive Protein / analysis
  • Collagen Diseases / blood*
  • Collagen Diseases / complications
  • Collagen Diseases / diagnosis
  • Collagen Diseases / metabolism
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Glycoproteins / blood*
  • Humans
  • L-Lactate Dehydrogenase / blood
  • Lung Diseases, Interstitial / blood*
  • Lung Diseases, Interstitial / complications
  • Lung Diseases, Interstitial / diagnosis
  • Lung Diseases, Interstitial / metabolism
  • Male
  • Middle Aged
  • Mucin-1
  • Mucins
  • Predictive Value of Tests
  • Prognosis


  • Antigens
  • Antigens, Neoplasm
  • Biomarkers
  • Glycoproteins
  • MUC1 protein, human
  • Mucin-1
  • Mucins
  • C-Reactive Protein
  • L-Lactate Dehydrogenase