title: Comparison of plasma interferon-gamma and antigen 60 immunoglobulin G in diagnosing pulmonary Mycobacterium tuberculosis infection.
abstract: BACKGROUND
  An elevated interferon-gamma (IFN-gamma) level has been reported in the plasma of patients with pulmonary tuberculosis. Serologic diagnosis of tuberculosis using Antigen 60 immunoglobulin G (A60 IgG) is a well-known diagnostic approach. This study evaluated plasma IFN-y compared to A60 IgG in diagnosing Mycobacterium tuberculosis.
  
  
  METHODS
  This study recruited 65 patients with tuberculosis and 59 controls. The plasma levels of A60 IgG and IFN-gamma were measured using enzyme-linked immunosorbent assay kits.
  
  
  RESULTS
  The cutoff values of IFN-gamma and A60 IgG tests were set at 0.137 pg/ml and 261.2 units. The sensitivity and specificity of the IFN-gamma test were 27.7% and 91.5%. The positive and negative predictive values of the IFN-gamma test were 53.4% and 78.3%. Moreover, the sensitivity and specificity of the A60 IgG test were 53.8% and 67.8%. The positive and negative predictive values of the A60 IgG test were 37.0% and 80.7%. Finally, the sensitivity and specificity of the combined A60 IgG and IFN-gamma tests were 64.6% and 62.7%. The positive and negative predictive values of the combined A60 IgG and IFN-gamma tests were 37.8% and 83.4%.
  
  
  CONCLUSIONS
  The combined tests did not achieve significant improvement in disease prediction. The A60 IgG test and IFN-gamma test had similar diagnostic value in pulmonary Mycobacterium tuberculosis infection.
authors.affiliation: Division of Pulmonary Medicine, Department of Internal Medicine, Chang Gung Memorial Hospital, Keelung, Taiwan, R.O.C. whanpyng@cgmh.org.tw
authors.forename: Huang-Pin
authors.initials: HP
authors.lastname: Wu
authors.forename: Chung-Ching
authors.initials: CC
authors.lastname: Hua
authors.forename: Chung-Chieh
authors.initials: CC
authors.lastname: Yu
authors.forename: Shao-Yun
authors.initials: SY
authors.lastname: Wu
mesh_terms: D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology*; D001500:BCG Vaccine / Q000276:immunology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007371:Interferon-gamma / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*; D014611:Vaccination
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001500:BCG Vaccine; D007074:Immunoglobulin G; C055539:mycobacterial A60 antigen; D007371:Interferon-gamma