Increased serum KL-6 levels induced by pulmonary mycobacterium avium complex infection in a patient with RA-associated lung disease

Koichi Waseda, Kazuki Ocho, Kou Hasegawa, Kosuke Kimura, Masaya Iwamuro, Yoshihisa Hanayama, Eisei Kondo, Nobuaki Miyahara, Fumio Otsuka

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2 Citations (Scopus)


KL-6 is a glycoprotein found predominantly on type II pneumocytes and alveolar macrophages, and often shows increased serum levels in patients with interstitial pneumonia. We report a case of mycobacterium avium complex (MAC) infection whose disease activity was correlated with KL-6 levels in serum. During treatment of rheumatoid arthritis (RA)-associated interstitial lung disease (ILD) with prednisolone, chest image findings improved in association with decreased KL-6 levels. Following tapering of prednisolone, chest image findings deteriorated again as levels of KL-6 increased, suggesting recurrence of RA-ILD. Bronchoscopic examination revealed active MAC infection. Treatment of MAC infection not only improved chest image findings but also decreased KL-6 levels in serum, suggesting that KL-6 was increased by active MAC infection by itself, not by recurrence of RA-ILD. To the best of our knowledge, this is the first documentation of KL-6 elevation in serum in association with active MAC infection.

Original languageEnglish
Pages (from-to)217-222
Number of pages6
JournalActa Medica Okayama
Issue number3
Publication statusPublished - 2016



  • Bronchial alveolar lavage
  • KL-6
  • Mycobacterium avium complex
  • Pulmonary nontuberculous mycobacterium infection
  • Rheumatoid arthritis-associated interstitial lung disease

ASJC Scopus subject areas

  • Medicine(all)
  • Biochemistry, Genetics and Molecular Biology(all)

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