Estimation of interleukin 6 levels as a potential biomarker among pulmonary tuberculosis patients for assessing disease severity

Abstract

Background: Mycobacterium tuberculosis (MTB), the causative agent of pulmonary tuberculosis (PTB), remains a major global health challenge, particularly in low-and middle-income countries, contributing to significant morbidity and mortality. Beyond microbial factors, host immune responses play a crucial role in disease progression. Cytokines such as interleukin-6 (IL-6), a pro-inflammatory mediator, are increasingly recognized as indicators of disease severity and bacterial burden. Materials and Methods: This study included 80 confirmed PTB patients to evaluate the potential role of IL-6 as a biomarker. Serum IL-6 levels were measured using enzyme-linked immunosorbent assay (ELISA). Concentrations were calculated using standard curves derived from mean optical density values. Results: MTB infection was confirmed in 72 participants, with rifampicin resistance detected in two cases. Serum IL-6 levels exhibited marked variability, ranging from 6.64–200 pg/mL. Elevated IL-6 levels were observed in patients with advanced disease and poorer clinical outcomes, while moderate levels were noted in patients with less severe disease. A positive correlation was identified between IL-6 levels, clinical severity, and bacterial burden. Conclusion: Serum IL-6 may serve as a valuable adjunct biomarker for assessing disease severity, monitoring therapeutic response, and predicting outcomes in PTB patients. Further large-scale, multicentric studies are warranted to validate its clinical utility and facilitate its integration into routine practice for disease stratification.