A New Diagnostic Test For Detecting Infection Of Mycobacterium Tuberculosis Based On In Vitro IFN-γ Release Assay By Whole Blood Culture: Its Establishment And Primary Application

Tuberculosis(TB) is caused by Mycobacterium tuberculosis(MTB) infection, which is a serious threat to human health,it could lead to chronic respiratory diseases. At present,tuberculosis shows a trend to expand.About 1/3 people all over the world have been infected with MTB,but the existing diagnostic methods are more or less defective,and their main problem is the low sensitivity and specivity.So we need a new TB diagnostic method to overcome the existing methods deficiencies.The immune system will be activated with mycobacterium tuberculosis infection. The body will generate specific effector T cells and memory T cells for MTB.T cell activation and cytokine secretion(such as IFN-γ) will be happened after the specific lymphocyte cells encountered with MTB.Based on this theory and also the references, this study established a new TB diagnostic test called "TB IFN-γrelease assay, TB-IGRA".TB-IGRA contains in vitro cell culture system and cytokine quantification system,with time-cosuming of about 24hrs.After clinical trials,it shows that the sensitivity of TB-IFN-γis 95.8%,and the specivity is 96.3%,which is better than former reagents.This reagent has a high sensitivity in not only tuberculosis but also extra-pulmonary tuberculosis(EPTB).The sensitivity in EPTB is 92.9%.This study also shows that there is a certain relationship between TB-IGRA results and the patient physical conditions.TB-IGRA results decreased when patients got healed,the negative conversion ratio is 53.8%,so TB-IGRA might be the indicator of the progression of the disease.A study on one TB outbreak incident shows that the results of this reagent is positive correlated with the exposure to TB.At the same time,the study shows that TB-IGRA has the same capacity as QFT to detect the carriers of tuberculosis.This study successfully established whole blood TB IFN-γrelease assay kit,and we have verified the relevant parameters have been met with our requirements.We found that some areas should be further studied when we used this kit for primary clinical validation,and follow-up study will be continued to verify the reliability and the clinical value of this reagent.