title: Interferon-gamma treatment kinetics among patients with active pulmonary tuberculosis.
abstract: BACKGROUND
  Interferon-γ (IFN-γ) is essential for defence against Mycobacterium tuberculosis; however, levels in patients with active tuberculosis (TB) and changes during treatment have not been documented in our tuberculosis patients in Nigeria, hence this study has been carried out.
  
  
  OBJECTIVE
  To determine variations, treatment kinetics, and predictive value of IFN-γ levels during treatment of active tuberculosis.
  
  
  METHODS
  Patients with pulmonary tuberculosis were recruited and subsequently followed up for 3 months during treatment with anti-TB. Peripheral blood was collected for IFN-γ assays, C-reactive protein and others followed by a Mantoux test. IFN-γ levels produced by stimulation with TB antigens were determined by ELISA and repeated measurement of IFN-γ were done at 1 and 3 months of anti-TB therapy. Chi Associations and correlations between IFN-γ were determined. Regression analysis was done to determine association between serial IFN-γ and treatment outcome.
  
  
  RESULTS
  We recruited 47 patients with active tuberculosis with a mean age of 34.8 ± 3.6 years and M:F ratio of 1.12:1. Six (11%) were HIV positive. The mean level of IFN-γ induced by TB antigens was 629 ± 114.1 pg/ml, higher for HIV-negative PTB patients compared with HIV-positive PTB patients, 609.78 ± 723.9 pg/ml and 87.88 ± 130.0 pg/ml, respectively, P-value = 0.000. The mean level of IFN-γ induced by TB antigen increased significantly from 629 ± 114.1 pg/ml to 1023.46 + 222.8 pg/ml, P-value = 0.03 and reduced to 272.3 ± 87.7 pg/ml by the third month on anti-TB drugs, P-value = 0.001. Negative correlation was observed between the mean of baseline and chest X-ray involvement, P = 0.03. There was no significant correlation between sputum smear grade with baseline and follow-up IFN-γ levels. Three-month IFN-γ level among cured patients were higher than those with treatment failure, regression analysis showed that it does not predict outcome.
  
  
  CONCLUSIONS
  IFN-γ may be useful in early detection and monitoring response; however, large scale studies are needed.
authors.affiliation: Department of Medicine, Obafemi Awolowo University and Teaching Hospitals, Ile Ife, Osun State, Nigeria.
authors.forename: Olanisun Olufemi
authors.initials: OO
authors.lastname: Adewole
authors.affiliation: Tuberculosis Immunology Unit, Medical Research Council Unit, Banjul, Gambia.
authors.forename: Martin O
authors.initials: MO
authors.lastname: Ota
authors.affiliation: Department of Medicine, Obafemi Awolowo University and Teaching Hospitals, Ile Ife, Osun State, Nigeria.
authors.forename: Greg E
authors.initials: GE
authors.lastname: Erhabor
authors.affiliation: Tuberculosis Immunology Unit, Medical Research Council Unit, Banjul, Gambia.
authors.forename: Patrick
authors.initials: P
authors.lastname: Owiafe
authors.affiliation: Department of Medicine, Obafemi Awolowo University and Teaching Hospitals, Ile Ife, Osun State, Nigeria.
authors.forename: Aliu
authors.initials: A
authors.lastname: Oladimeji
authors.affiliation: Department of Medicine, Obafemi Awolowo University and Teaching Hospitals, Ile Ife, Osun State, Nigeria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Obaseki
keywords: Interferon-gamma; treatment outcome; tuberculosis