Serum Levels of Interleukin-12 and Interferon Gamma in Pediatric Tuberculosis: A Clinico-Microbiological Correlation

Abstract

Objective: The interleukin-12/interferon-γ (IL-12/IFN-γ) pathway is the most validated cytokine pathway regulating Mycobacterium tuberculosis infection. The role of IL-12/IFN-γ axis in protecting against tuberculosis (TB) is exhibited in people having mutations in genes encoding these cytokines. We aimed to study the serum levels of IL-12 and IFN-γ in pediatric tuberculosis and their correlation with clinical and microbiological features. Material and Methods: A case-control study was conducted on 60 microbiologically confirmed (smear and/or culture and/or cartridge-based nucleic acid amplification test) or clinically diagnosed (based on clinical features and radiography and/or contact history and/or Mantoux test with/without microbiological confirmation) pediatric TB patients ≤12 years. Serum interleukin-12 and interferon-gamma levels were estimated using enzyme-linked immunosorbent assays.Thirty age- and sex-matched controls were also included in the study. Results: The median IL-12 levels were lower in our pediatric TB patients (488.1 pg/ml) compared to controls (784.8 pg/ml). However, the IFN-γ/IL-12 ratios were significantly higher among the TB patients as compared to the controls. Moreover, the levels of interleukin-12 and interferon gamma were significantly lower in cases with no evidence of TB on chest radiography. IL-12 was significantly lower in patients with hydrocephalus and enlarged ventricles. Higher levels of IL-12 and IFN-γ were associated with positive results by conventional microbiological techniques. Conclusion: The serum IFN-γ level and the IFN-γ/IL-12 ratio were significantly higher in children with TB compared to the controls in this study. Higher IL-12 and IFN-γ levels as well as IFN-γ/IL-12 ratios were associated with positive results by conventional microbiological techniques. Further studies on larger sample sizes could help evaluate the usefulness of interleukin-12 and interferon-γ as potential markers of severity and prognosis in pediatric TB.