Role of Biomarkers (Interleukins (IL)- 2,5,6,16,17,1ß) in Saliva and Serum for Diagnosis of Pulmonary Tuberculosis and for Monitoring Response to Intensive Phase Treatment

Introduction: Majority of the currently used diagnostic tests for Pulmonary Tuberculosis (PTB) have variability in sensitivity and specificity in diagnosing PTB. Therefore, evaluating new biomarkers in easily obtainable samples like serum and saliva can contribute to the diagnosis of PTB.

Aim: To evaluate the role of Interleukins(IL)- 2,5,6,16,17,1βin the diagnosis of PTB by comparing their levels in Other Respiratory Diseases (ORD) group and monitoring the response to treatment in PTB group.

Materials and Methods: This prospective observational study was conducted between January 2021 to May 2022 in a tertiary care hospital in New Delhi, India. A total of 80 cases were taken of which 40 cases of PTB and 40 cases having diagnosis of ORD were studied. IL-2,5,6,16,17,1βlevels were measured in saliva and serum using Enzyme Linked Immune Sorbent Assay (ELISA) kits. These IL were also measured in diagnosed PTB patients in serum and saliva after two months of treatment. Statistical analysis was done using Statistical Package for the Social Sciences (SPSS) version 16.0. Kruskal Wallis H Test, Wilcoxon signed-rank sum test, Chi-square test and Fisher’s exact test were applied at appropriate areas and a p-value <0.05 was taken as significant.

Results: On comparing the levels of IL between serum and saliva in PTB group at baseline, IL-2, IL-17 levels were higher in serum while IL-5, IL-1βlevels were higher in saliva with these results being statistically significant (p-value <0.001). However, after two months of treatment, the levels of IL-2, IL-16 decreased significantly in both serum and saliva whereas IL-17 level decreased significantly only in serum after treatment. None of the IL showed significant difference in levels between serum and saliva in PTB and ORD groups.

Conclusion: The diagnostic role of IL in PTB could not be established whereas IL-2, IL-16 and IL-17 can be used for monitoring response to treatment as the levels decreased significantly with treatment.