title: Increased Serum KL-6 Levels Induced by Pulmonary Mycobacterium Avium Complex Infection in a Patient with RA-associated Lung Disease.
abstract: 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.
authors.affiliation: Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan.kazukazun2006@yahoo.co.jp.
authors.forename: Koichi
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authors.lastname: Waseda
authors.forename: Kazuki
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authors.forename: Kou
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authors.lastname: Kimura
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authors.lastname: Iwamuro
authors.forename: Yoshihisa
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authors.lastname: Hanayama
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authors.lastname: Kondo
authors.forename: Nobuaki
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authors.lastname: Miyahara
authors.forename: Fumio
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authors.lastname: Otsuka