Level of Interferon Gamma in the Blood of Tuberculosis Patients

Background: Interferon gamma (IFN-γ), a cytokine produced by a variety of cells is involved in the immune response against M. tuberculosis. It activates the production of other cytokines and molecules that kill mycobacterium. IFN-γ also has diagnostic role in identification of active and latent tuberculosis. Objective: To determine the level of IFN-γ in the blood of TB patients. Methods: Ninety-one subjects were selected, including 54 active TB patients and 37 healthy controls. Among 54 TB patients, 27 had confirmed TB and 27 were clinically diagnosed as having TB. IFN-γ concentration was determined in their blood by an ELISA technique. Results: In TB patients, Mean + SD of IFN-γ was 48.69 + 28.78 pg/ml while it was 12.99 + 5.70pg/ml in the control group (p <0.001). Significant differences in the level of IFN-γ were observed among confirmed TB patients, clinically diagnosed TB patients and the control group (Mean + SD 59.68 + 28.78, 36.85 + 24.76 and 12.99 + 5.70 pg/ml, respectively). Furthermore, a significant negative correlation was observed between the concentration of IFN-γ in TB patients and the duration of antituberculosis therapy. Conclusion: IFN-γ level was high in both clinically diagnosed and confirmed TB patients as compared to a control group. Measurement of IFN-γ production is helpful to diagnose active tuberculosis, but further research is required.