Significance of IFN‐ɤ/IL‐2 Ratio as a Circulating Diagnostic Biomarker in Extrapulmonary Tuberculosis |
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| Authors: | N. Goyal B. Kashyap I. R. Kaur |
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| Affiliation: | 1. Department of Microbiology, University College of Medical Sciences & Guru Teg Bahadur Hospital, New Delhi, India;2. Department of Microbiology, Maulana Azad Medical College and Associated Hospitals, New Delhi, India |
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| Abstract: | Extrapulmonary tuberculosis (EPTB) remains a challenging diagnosis both for clinicians and microbiologists. We hypothesized that the profile of IFN‐?/IL‐2 ratio in clinically diagnosed cases of EPTB would be distinct from that of age‐ and sex‐matched healthy controls. Therefore, in our study, we have assessed the ratio of serum levels of IFN‐? and IL‐2 in clinically diagnosed cases of EPTB to assess their potential role as diagnostic biomarkers. Sixty‐nine (69) clinically confirmed EPTB cases and 69 age‐ and sex‐matched healthy controls were included in the study. All the extrapulmonary specimens were subjected to Ziehl–Neelsen staining for acid‐fast bacilli and culture on Lowenstein–Jensen (LJ) medium. Detection of serum levels of IFN‐? and IL‐2 was carried out using commercially available ELISA kits following manufacturers' instructions. The ratio of serum levels of IFN‐? and IFN‐?/IL‐2 was discriminative for the diagnosis of EPTB cases (p < 0.001), although the same was not observed with IL‐2 (p > 0.05). Distribution of all biomarkers significantly differed between culture‐positive and culture‐negative cases (p < 0.05). Among the smear‐positive and smear‐negative ones, only IFN‐? and IFN‐?/IL‐2 ratio could significantly differentiate (p < 0.05). Ratio of IFN‐? and IL‐2 rather than the individual levels was the best discriminatory biomarker with the highest area under the ROC curve. Although IFN‐? and IFN‐?/ IL‐2 ratio could aid in the diagnosis of EPTB, IL‐2 has a limited utility in the diagnosis of EPTB. Further elaborate studies to validate these results are required. |
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