Interleukin-6 Blood Levels in Sensitive and Multiresistant Tuberculosis

Interleukin-6 (IL-6) is a proinflammatory cytokine implicated in the immunopathogenesis of tuberculosis (TB). Multidrug resistance in tuberculosis is recognized worldwide as an important public health issue. The mechanism underlying TB pathogenesis in general and drug resistance in particular is not well understood, but it may be that IL-6 is one factor that enhances pathology in drug-resistant TB. The purpose of this study was to identify patterns of IL-6 production in active pulmonary TB with different sensitivity to standard drug therapy. IL-6 blood levels were studied in 38 patients with active pulmonary TB: 23 patients were very sensitive to specific chemotherapy (STB), and 15 were multiresistant (MDRTB). An ELISA assay (Biossource) was used to quantify IL-6 in the sera of 38 TB patients and 63 healthy blood donors. The STB group was composed of 16 males (73.9%) and 7 females, MDRTB by 9 males (60%) and 6 females, and control group by 51 males (81%) and 12 females. The results showed a significant increase in IL-6 concentration in TB (median = 4.3 pg/ml, range 0.5-24) compared to that of healthy individuals (median = 0.5 pg/ml, range 0-2.8, p < 0.001). Additionally, IL-6 concentrations were increased in both STB (median = 4.1 pg/ml, range 0.5-24) and MDRTB (median = 5.1 pg/ml, range 0.5-12) groups in relation to controls (p < 0.001). In contrast, significant differences were not observed between STB and MDRTB groups (p > 0.05). IL-6 levels were increased in pulmonary tuberculosis, independent of drug resistance.