title: Using the TBAg/PHA ratio in the T-SPOT(®).TB assay to distinguish TB disease from LTBI in an endemic area.
abstract: METHODS
  An important limitation of the T-SPOT(®).TB assay is its inability to distinguish active tuberculosis (TB) from latent tuberculous infection (LTBI).
  
  
  OBJECTIVE
  We proposed a new calculation method for the T-SPOT assay and assessed its effect on distinguishing active TB from LTBI.
  
  
  METHODS
  A total of 162 active TB patients and 97 LTBI individuals were diagnosed according to conventional tests and the T-SPOT assay.
  
  
  RESULTS
  The results of early secreted antigenic target 6 (ESAT-6) and culture filtrate protein 10 (CFP-10) in T-SPOT cannot be recommended for distinguishing TB from LTBI. The number of phytohaemagglutinin (PHA) spot-forming cells (sfc) in the T-SPOT assay was reduced in active TB patients. The ESAT-6/PHA or CFP-10/PHA ratios in active TB patients were significantly higher than in individuals with LTBI. Using 0.295 as the threshold ratio of Mycobacterium tuberculosis-specific antigen (TBAg) sfc to PHA sfc (TBAg/PHA ratio, the larger of ESAT-6/PHA and CFP-10/PHA), the sensitivity and specificity were 82.1% and 90.7% in distinguishing active TB from LTBI. The TBAg/PHA ratio might also be used to monitor the effect of anti-tuberculosis treatment.
  
  
  CONCLUSIONS
  Calculating the TBAg/PHA ratio might have the potential to diagnose active TB and distinguish TB disease from LTBI.
authors.affiliation: Department of Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: F
authors.initials: F
authors.lastname: Wang
authors.affiliation: Department of Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: H-Y
authors.initials: HY
authors.lastname: Hou
authors.affiliation: Department of Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: S-J
authors.initials: SJ
authors.lastname: Wu
authors.affiliation: Department of Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Zhu
authors.affiliation: Department of Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: M
authors.initials: M
authors.lastname: Huang
authors.affiliation: Department of Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: B
authors.initials: B
authors.lastname: Yin
authors.affiliation: Department of Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: J
authors.initials: J
authors.lastname: Huang
authors.affiliation: Department of Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Y-Y
authors.initials: YY
authors.lastname: Pan
authors.affiliation: Department of Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: L
authors.initials: L
authors.lastname: Mao
authors.affiliation: Department of Clinical Laboratory, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Z-Y
authors.initials: ZY
authors.lastname: Sun
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000942:Antigens, Bacterial / Q000032:analysis*; D000995:Antitubercular Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000032:analysis*; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D005260:Female; D006801:Humans; D059425:Interferon-gamma Release Tests; D055985:Latent Tuberculosis / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D010835:Phytohemagglutinins / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D000942:Antigens, Bacterial; D000995:Antitubercular Agents; D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D010835:Phytohemagglutinins