Comparison of Interleukin 17A and Interleukin-18 Cytokines During Active and Latent TB Infection in Iraqi Patients

Abstract

Introduction: Despite international control programs, tuberculosis remains a public health issue. People with latent TB infection (LTBI) significantly increase the number of active tuberculosis (TB) cases and carry a lifelong risk of developing the disease. Therefore, the present study aims to determine the changes in cytokine production at two phases during the development of active pulmonary and latent tuberculosis infection and to evaluate their role as predictive markers in active and latent infections.Method: Blood specimens were collected from 60 patients with active pulmonary TB, 60 cases with latent TB infection and 40 healthy controls to obtain serum. ELISA kit for IL-17A and IL18 was used to determine the concentrations of IL-17A and IL18 according to the manufacturer's instructions (Elabscience / China).Result: The results of the current study found that the mean serum concentration of interleukin-18 was significantly higher in cases with Active pulmonary tuberculosis compared to cases with latent TB infection and healthy control, respectively (P<0.001), also the mean serum concentration of IL-18 was significantly higher in subjects with latent TB infection as compared to healthy control ( P<0.001). Also, the present study found that the mean serum concentration of IL-17A showed an insignificant variation in cases with Active pulmonary TB compared to healthy control (P< 0.069). In contrast, the mean serum concentration of IL-17A was significantly higher in subjects with latent TB infection as compared to healthy control(P<0.002) and Active pulmonary TB (P<0.001)Conclusion: A comparison of latent and active tuberculosis cases may provide some insight into factors that shield them from disease development, as well as new insights into the roles of interleukin -17A and interleukin -18 at two critical stages of the M. tuberculosis infection. These findings suggest that IL-17A and IL18 play distinct roles in two phases of tuberculosis infection and can potentially be used to develop novel diagnostics. The IL-18 ELISA results revealed a highly significant difference between the three groups. All of this information allows to distinguish TB patients and LTBI from healthy controls. Furthermore, the current findings indicated that IL-17A could be alternative biomarker for LTBI diagnosis.