Evaluation of a Whole Blood Chemiluminescent Immunoassay of Interferon-gamma Inducible Protein 10 (IP-10) for Diagnosis of Tuberculosis Patients.

BACKGROUND: The rapid diagnosis of bacterium-negative pulmonary TB and extra pulmonary TB is a significant problem in clinical practice.

METHODS: 466 individuals were prospectively enrolled, 247 patients with TB, 147 with non-tuberculous pulmonary disease, and 65 healthy controls. Whole blood was stimulated in vitro with rCFP10/ESAT6 antigen of Mycobacterium tuberculosis. A chemiluminescence immunoassay was used to detect the stimulated release of interferon-gamma inducible protein 10 (IP-10), and a receiver operating characteristic (ROC) curve was drawn to determine cutoff value for diagnosing TB and to evaluate the diagnostic efficacy of the IP-10 assay.

RESULTS: The antigen-specific release of IP-10 in the TB group was significantly higher than in the non-tuberculous pulmonary disease group (p < 0.001) and the healthy control group (p < 0.001). The IP-10 test correctly detected more cases of pulmonary TB and extra-pulmonary TB than the acid-fast staining microscopy examination (AFB). The sensitivity, specificity, and diagnostic efficiency for IP-10 were 75.3%, 84.9%, and 79.7%, respectively. Patients with TB and cancer comorbidity produced significantly higher levels of the TB-specific IP-10 release compared to the other groups (p < 0.05), whereas respiratory disease patients produced lower levels than the healthy controls (p > 0.05).

CONCLUSIONS: Our findings indicate high sensitivity and specificity of IP-10 as a novel biomarker for TB in China.