Latent tüberküloz enfeksiyonu tanisinda ip-10 testinin performansinin değerlendirilmesi

Interferon gamma release assays (IGRAs) are cell-mediated immunity based tests that measure IFN-γ responses specific to Mycobacterium tuberculosis antigens. Though IGRAs far surpass tuberculin skin test in specificity, they hardly are superior to skin test in terms of sensitivity. The interferon-γ inducible protein (IP)-10, as its name implies, increase in line with IFN-γ in every inflammatory reaction, which makes it a potential alternative chemokine to IFN-γ. In this study, we aimed to assess the sensitivity and specificity of the IP-10 release assay (IPRA) for the diagnosis of latent tuberculosis infection. For this purpose, 84 newly diagnosed, microbiologically confirmed active tuberculosis patients and 57 patients with various respiratory conditions other than tuberculosis constituted the study population. All patients were immunocompetent and older than 17 years of age. Similar to tuberculin skin test, we incubated antigen and mitogen stimulated blood tubes, and the nil tubes, for 48 hours before measuring the IP-10 responses. The median IP-10 levels in plasma were (3269.6pg/ml) and (18.1pg/ml) in the active tuberculosis and the non-tuberculosis patients, respectively. Analysis of the results by receiver-operating-curve analysis showed that the IP-10 assay had a high diagnostic accuracy, with an AUC of 0.962 (p ˂ 0.001). The cut-off for our IPRA was found 439pg/ml at maximum Youden Index (sensitivity + specificity - 1). At this cut-off, the sensitivity and specificity was found 89.3% with 98.2 %, respectively. This study supports previous findings and shows that the IPRAs can be used as stand-alone diagnostic biomarker for the diagnosis of latent tuberculosis infection.