Baseline serum cytokine levels as early predictive markers of mycobacterial clearance in terms of sputum conversion in adult pulmonary tuberculosis

Background: Predictor biomarkers of clinical outcome can help identify tuberculosis patients with a higher risk for poor outcomes at the baseline itself. Serum cytokines can be predictive of treatment outcomes as well as the disease severity of tuberculosis patients. Objective: The aim is to study baseline serum IFN-γ, TNF-α, IL-6, and CRP levels concerning sputum conversion in pulmonary TB. Patients and methods: ZN smears and cultures were taken from sputum samples of fifty smear-positive pulmonary TB (SPPTB) patients at baseline and after the intensive phase (IP) of treatment. Sera for cytokines and CRP estimation by ELISA were done at baseline for fifty TB cases and twenty controls. Results: The mean serum CRP and TNF-a, IL-6, and IFN-g levels in fifty SSPTB patients were 68.18 ± 22.24 mg/l, 43.49 ± 40.80 pg/ml, 34.69 ± 23.94 pg/ml, and 39.74 ± 29.41 pg/ml respectively. The smear and culture conversion rate at the end of IP was 94%. Baseline cytokine levels were significantly higher in delayed sputum converters. A significant difference in baseline levels with smear grading (except IFN-g), colony count, and time to culture positivity was found for all the biomarkers. Conclusion: CRP, TNF-a, IFN-g, and IL-6 may be useful for predicting treatment response, with further studies required for validation.