title: Serum B cell-activating factor (BAFF) level in connective tissue disease associated interstitial lung disease.
abstract: BACKGROUND
  Interstitial lung diseases (ILDs) are common in patients with connective tissue diseases (CTDs). Although the diagnosis of an underlying CTD in ILD (CTD-ILD) affects both prognosis and treatment, it is sometimes difficult to distinguish CTD-ILD from chronic fibrosing interstitial pneumonia (CFIP). B cell-activating factor belonging to the tumour necrosis factor family (BAFF) plays a crucial role in B cell development, survival, and antibody production.
  
  
  METHODS
  We examined serum levels of BAFF, surfactant protein D (SP-D), and Krebs von den Lungen-6 (KL-6) in 33 patients with CTD-ILD, 16 patients with undifferentiated CTD-ILD, 19 patients with CFIP, and 26 healthy volunteers. And we analysed the relationship between serum BAFF levels and pulmonary function, as well as the expression of BAFF in the lung tissue of patients with CTD-ILD.
  
  
  RESULTS
  Serum levels of BAFF were significantly higher in CTD-ILD patients compared to healthy subjects and CFIP patients. However, there were no significant differences in serum levels of SP-D and KL-6. Furthermore, serum BAFF levels in CTD-ILD patients were inversely correlated with pulmonary function. BAFF was strongly expressed in the lungs of CTD-ILD patients, but weakly in normal lungs.
  
  
  CONCLUSIONS
  This is the first study to demonstrate that serum BAFF levels were significantly higher in CTD-ILD patients compared to healthy subjects and CFIP patients. Furthermore, serum BAFF levels were correlated with pulmonary function. We consider that serum BAFF levels in patients with CTD-ILD reflect the presence of ILDs disease activity and severity.
  
  
  CONCLUSIONS
  These finding suggest that BAFF may be a useful marker for distinguishing CTD-ILD from CFIP.
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. k5064132@kadai.jp.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hamada
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. samukawa@m3.kufm.kagoshima-u.ac.jp.
authors.forename: Takuya
authors.initials: T
authors.lastname: Samukawa
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. kuma@m2.kufm.kagoshima-u.ac.jp.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kumamoto
authors.affiliation: Department of Molecular and Cellular Pathology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan. kh1966@m2.kufm.kagoshima-u.ac.jp.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Hatanaka
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. minimini@m3.kufm.kagoshima-u.ac.jp.
authors.forename: Go
authors.initials: G
authors.lastname: Tsukuya
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. masukichioji@yahoo.co.jp.
authors.forename: Masuki
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. machida@m.kufm.kagoshima-u.ac.jp.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Machida
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. maswata@m.kufm.kagoshima-u.ac.jp.
authors.forename: Masaki
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. keim@m.kufm.kagoshima-u.ac.jp.
authors.forename: Keiko
authors.initials: K
authors.lastname: Mizuno
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. ikkou@m2.kufm.kagoshima-u.ac.jp.
authors.forename: Ikkou
authors.initials: I
authors.lastname: Higashimoto
authors.affiliation: Clinical Research Center, National Hospital Organization Kinki-Chuo Chest Medical Center, Osaka, Japan. giichiyi@aol.com.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: Department of Pulmonary Medicine, Graduate School of Medical and Dental Sciences, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan. inoue-pulm@umin.net.
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Inoue
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D053264:B-Cell Activating Factor / Q000378:metabolism*; D016022:Case-Control Studies; D003240:Connective Tissue Diseases / Q000150:complications; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000175:diagnosis / Q000378:metabolism*; D008168:Lung / Q000378:metabolism* / Q000503:physiopathology; D017563:Lung Diseases, Interstitial / Q000150:complications / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018396:Mucin-1 / Q000097:blood; D037663:Pulmonary Surfactant-Associated Protein D / Q000097:blood; D012720:Severity of Illness Index; D014797:Vital Capacity
chemical_list: D053264:B-Cell Activating Factor; C060192:MUC1 protein, human; D018396:Mucin-1; D037663:Pulmonary Surfactant-Associated Protein D; C505719:TNFSF13B protein, human