The utility of the interferon gamma-inducible protein-10 (IP-10) level in bronchoalveolar lavage and blood in the diagnosis of tuberculosis

Introduction: Control of TB depends on early detection and treatment of active cases. Aim of the work: Investigating the utility, sensitivity and specificity of interferon gamma inducible protein IP-10 in both blood and bronchoalveolar lavage (BAL) in the diagnosis of TB infection in clinically suspected patients. Methods: Thirty patients with clinical and/or radiological suspicion of pulmonary tuberculosis and negative sputum smear for AFB with Z–N stain were included in the study. BAL and blood samples were sent for the estimation of the level of interferon gamma inducible protein IP-10. Results: IP-10 levels in both blood and BAL were significantly higher in TB patients (P = 0.005 and 0.007 respectively). Sensitivity of IP-10 in blood was 100% and specificity was 60%. Positive predictive value was 56%, negative predictive value was 100% and accuracy was 73%. Sensitivity of IP-10 in BAL was 100% and specificity was 35%. Positive predictive value was 44%, negative predictive value was 100% and accuracy was 57%. Sensitivity of IP-10 in blood and BAL were similar (100%) and both were more sensitive than tuberculin skin test (TST) (sensitivity 67%). Detection of IP-10 in blood (specificity = 60%) was more specific than its detection in BAL (specificity = 35%). On the other hand, specificity of detection of IP-10 in blood (60%) was comparable to the tuberculin test (specificity = 62%). Conclusion: Interferon gamma inducible protein IP-10 may help in detecting M. tuberculosis infection and monitoring disease activity and efficacy of therapy