Interleukin-10 and Interferon Gamma as Prognostic Markers in Pulmonary Tuberculosis

Background: Mycobacterium tuberculosis (Mtb) infection is considered one of the most common causes of human mortality in the world. Many studies had done to explore the role of host defense in controlling the disease but many points are still unclear and need further researches. Many of pro-inflammatory and anti-inflammatory cytokines play a role in the generation and development of tuberculosis (TB) illness. Interferon gamma (IFN-γ) and interleukin-10 (IL-10) have contradictory and conflicting roles in correlation to Mtb infection severity and response to therapy. Objectives: The aim of our study was to estimate the relationship between IFN-γ and IL-10 levels and the different stages of TB and the possible effects of TB therapy on their levels. Methodology: Our study included 40 patients with active pulmonary TB and a control group of 40 healthy individuals. The levels of IFN-γ and IL-10 were measured in the patients at the start of therapy and after 3 and 6 months of TB therapy using enzyme-linked immune-sorbent assay (ELISA). Results: IFN-γ assessment by Quantiferon Gold in Tube test (QFT-GIT), for the pulmonary TB patients was higher than 0.35 IU/ml, so all patients were considered positive at the beginning of therapy. IL-10 was higher in TB patients than the control persons and the difference between the TB patients and the control persons was significant (p value <0.05). After 6 months of treatment, 6 cases not improved with treatment. IFN-γ was still high in those patients and didn't decline after 3 and 6 months of TB therapy as happened in the remaining 34 patients. The mean serum level of IL-10 declined in improved patients after therapy. However, in those 6 resistance patients, IL-10 still high after 6 months of treatment (p value < 0.05). Finally, IFN-γ didn't show difference in correlation with the disease severity, while IL-10 showed higher values with the advanced stage of Mtb (stage 3).  Conclusion: IL-10 and IFN-γ could be used as prognostic markers for the success of TB therapy, but only IL-10 shows a correlation with the severity of TB infection.