Rapid Diagnosis of Tuberculosis Infection by Detecting Interferon-gamma in Blood Samples - การตรวจการติดเชื้อวัณโรคอย่างรวดเร็วโดยการตรวจสารแกมมาอินเตอร์เฟอรอนในตัวอย่างเลือด

Abstract

          Early and effective diagnosis of tuberculosis has been considered as an essential tool for tuberculosis control program. Among cases of tuberculosis and persons with Mycobacterium tuberculosis infection, there are cell - mediated immune response towards tuberculosis infection, resulted in production of interferon gamma (IFN-γ) which being triggered by M. tuberculosis specific antigens. This study was aimed at detection of IFN-γ by using QuantiFERON-TB test to rapidly diagnose M. tuberculosis infection among study population. In a group of clinically diagnosed tuberculosis patients, 50 of 60 subjects had IFN-γ more than 0.35 IU/ml which indicated status of active infectious tuberculosis. In addition, the results from 50 household contacts showed positive in 14 individuals indicating asymptomatic tuberculosis infection. Study in control group of 20 healthy volunteers or foreigners revealed 2 individuals having IFN-γ higher than 0.35 IU/ml. The analysis of the quality of the assay was performed based on standard soluble IFN-γ that was used to construct standard curves at the concentrations of 4.0, 1.0, 0.25, and 0 IU/ml in each analysis. The mean
OD450 of standard controls were 0.930, 0.271, 0.103 and 0.045, respectively which were in an acceptable range and standards at the concentration of 4.0 IU/ml had a value of OD450 ≥ 0.600 and ≤0.150 at 0 IU/ml as indicated by the instruction of the test. Comparing results of diagnosis of tuberculosis by QuantiFERON-TB and bacteriological examination of samples will confirm the
accuracy of the analytical examination and support clinical diagnosis. It was concluded that IFN-γ test by QuantiFERON-TB was useful in rapid diagnosis of active tuberculosis and in early detection of tuberculosis infection.
Key words: tuberculosis, QuantiFERON-TB, IFN-gamma