Consistency of two interferon gamma release assay tests / 中华检验医学杂志

ABSTRACT

Objective:The results of the two interferon-gamma release assay tests were compared, so as to provide reference for the laboratory to choose the detection method.Methods:Double blood samples of 96 suspected TB patients hospitalized in Civil Aviation General Hospital from July 2018 to December 2019 were collected, providing for TB specific antigen stimulation test by QIAGEN kit and Autobio kit respectively. ELISA and chemiluminescence were used to detect interferon-gamma, and the results were determined according to the manufacturer′s instructions. Based on the clinical or bacteriological evidence for diagnosis of tuberculosis, the consistency of the two kits was compared, and the diagnostic efficacy of tuberculosis was evaluated. At the same time, 60 samples of plasma stimulated by TB specific antigen in QIAGEN kit were randomly selected to detect interferon-gamma by ELISA and chemiluminescence respectively, and the consistency between the two interferon-gamma detection systems was compared. The Kappa coefficient were used to measure the consistency of the results. The ordinary linear regression and Bland-Altman plots were performed to show the differences of IFN-γ data between assays.Result:In 96 samples, the sensitivity and specificity of QIAGEN test were 81.82% (18/22) and 74.32% (55/74), and that of Autobio test were 72.73% (16/22) and 70.27% (52/74), respectively. The results of the two systems were consistent, Kappa value was 0.847, P<0.05. The area under ROC curve of QIAGEN test for diagnosis of tuberculosis was 0.807 (95% confidence interval 0.702-0.911), while that of Autobio test was 0.765 (95% confidence interval 0.640-0.889). Comparing the results of two systems for detecting interferon-gamma in the same plasma, the results of two systems were in good agreement ( R2=0.97, P<0.05); but there were significant differences in the levels of interferon-gamma in the same patient sample after stimulation with different negative and positive tubes ( R2=0.41, P<0.05). Conclusion:The results of γ-interferon release assay test of Autobio system and QIAGEN system are in good agreement, and the results of γ-interferon release assay test of the two systems are also in good agreement. Different amount of antigen coating, titer and test system may be responsible for the different release of interferon-gamma.