title: Serodiagnosis of Mycobacterium avium complex pulmonary disease in rheumatoid arthritis.
abstract: BACKGROUND
  Mycobacterium avium complex (MAC) pulmonary disease (PD) is often difficult and complicated to diagnose or to discriminate from follicular bronchitis, bronchiectasis, or other conditions associated with rheumatoid arthritis (RA) lung in the clinical setting.
  
  
  OBJECTIVE
  We investigated whether a serologic test for anti-glycopeptidolipid (GPL) antibody was useful for distinguishing MAC-PD from RA lung in diagnosis.
  
  
  METHODS
  Serum IgA antibody to MAC-specific GPL core antigen was measured by an enzyme immunoassay. Antibody levels were measured in sera from 14 RA patients with MAC-PD (RA + MAC), 20 RA patients with bronchial or bronchiolar lesions without MAC-PD (RA w/o MAC), 20 RA patients without pulmonary lesions (RA only), and 25 healthy volunteers (HV).
  
  
  RESULTS
  The levels of serum anti-GPL antibodies were higher in the RA + MAC group than in the RA w/o MAC, RA-only, and HV groups (2.87 ± 2.83 vs. 0.50 ± 0.45, 0.31 ± 0.24, and 0.38 ± 0.10 U/ml, respectively; p < 0.001). With the cutoff point in receiver-operating characteristic analysis set at 0.7 U/ml, the serologic test differentiated RA + MAC from RA w/o MAC with a sensitivity of 100% and specificity of 90%.
  
  
  CONCLUSIONS
  This serologic test for anti-GPL antibody is useful for diagnosing MAC-PD in RA.
authors: Department of Integrated Pulmonology, Tokyo Medical and Dental University, Tokyo, Japan.
authors: Yoshitoshi
authors: Y
authors: Komazaki
authors: Yasunari
authors: Y
authors: Miyazaki
authors: Toshihide
authors: T
authors: Fujie
authors: Hiroyuki
authors: H
authors: Sakashita
authors: Kimitake
authors: K
authors: Tsuchiya
authors: Meiyo
authors: M
authors: Tamaoka
authors: Yuki
authors: Y
authors: Sumi
authors: Yuichiro
authors: Y
authors: Maruyama
authors: Toshihiro
authors: T
authors: Nanki
authors: Naohiko
authors: N
authors: Inase
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D015270:Mycobacterium avium-intracellulare Infection / Q000175:diagnosis*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012698:Serologic Tests