title: Sero-diagnosis of Mycobacterium avium complex lung disease using serum immunoglobulin A antibody against glycopeptidolipid antigen in Taiwan.
abstract: BACKGROUND
  Lung disease (LD) due to non-tuberculous mycobacteria is an important clinical concern. Mycobacterium avium complex (MAC) is one of the most common causative agents but the diagnosis of MAC-LD remains challenging. Detection of serum IgA antibody against MAC glycopeptidolipid (GPL) has recently been shown to improve the diagnosis of MAC-LD, but has yet to be validated worldwide.
  
  
  METHODS
  This prospective study was conducted in a tertiary referral center in northern Taiwan and enrolled patients with MAC-LD, MAC contamination, other lung diseases, and control subjects. Serum immunoglobulin A (IgA) antibody against MAC-GPL was detected in the participants and its specificity and sensitivity was assessed.
  
  
  RESULTS
  There were 56 patients with MAC-LD, 11 with MAC contamination, 13 M. kansasii-LD, 26 LD due to rapidly-growing mycobacteria (RGM), 48 pulmonary tuberculosis, and 42 household contacts of patients with TB. Patients with MAC-LD were older and 32% of them had an underlying co-morbidity. By logistic regression, serum MAC-GPL IgA level was an independent predictor of MAC-LD among the study subjects and those with culture-positive specimens for MAC. By the receiver operating characteristic curve, serum MAC-GPL IgA had a good power to discriminate MAC-LD from MAC contamination. Under the optimal cut-off value of 0.73 U/mL, its sensitivity and specificity were 60% and 91%, respectively. Among MAC-LD patients, presence of co-morbidity was associated with MAC-GPL <0.73 U/ml in logistic regression analysis.
  
  
  CONCLUSIONS
  Measurement of serum anti-MAC-GPL IgA level is useful for the diagnosis of MAC-LD. However, its implement in clinical practice for immuno-compromised hosts needs careful consideration.
authors.affiliation: Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan ; Department of Traumatology, National Taiwan University Hospital, Taipei, Taiwan ; Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Chin-Chung
authors.initials: CC
authors.lastname: Shu
authors.forename: Manabu
authors.initials: M
authors.lastname: Ato
authors.forename: Jann-Tay
authors.initials: JT
authors.lastname: Wang
authors.forename: Ruwen
authors.initials: R
authors.lastname: Jou
authors.forename: Jann-Yuan
authors.initials: JY
authors.lastname: Wang
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Hsin-Chih
authors.initials: HC
authors.lastname: Lai
authors.forename: Chong-Jen
authors.initials: CJ
authors.lastname: Yu
authors.forename: Li-Na
authors.initials: LN
authors.lastname: Lee
authors.forename: Kwen-Tay
authors.initials: KT
authors.lastname: Luh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology*; D000942:Antigens, Bacterial / Q000276:immunology*; D005260:Female; D006001:Glycoconjugates / Q000276:immunology; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D015269:Mycobacterium avium Complex / Q000276:immunology*; D015270:Mycobacterium avium-intracellulare Infection / Q000175:diagnosis* / Q000276:immunology*; D018410:Pneumonia, Bacterial / Q000175:diagnosis* / Q000276:immunology*; D011446:Prospective Studies; D012372:ROC Curve; D012307:Risk Factors; D012680:Sensitivity and Specificity
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D006001:Glycoconjugates; D007070:Immunoglobulin A