Abstract
Background: Interferon-gamma (IFN-γ) release assays (IGRAs) are useful for the diagnosis of Mycobacterium tuberculosis infection. Current IGRAs use either enzyme-linked immunosorbent assay (ELISA) or enzyme-linked immunospot assay, which require complex procedures and techniques to determine IFN-γ secretion. We aimed to compare the usefulness of the easy-to-use lateral flow assay (LFA) with that of the QuantiFERON-TB Gold In-Tube (QFT-GIT) or QuantiFERON-TB Gold Plus (QFT-plus) ELISAs for detecting IFN-γ, produced by the blood T cells stimulated by tuberculosis (TB) antigen. Methods: Following informed consent, 176 participants, including health care workers such as TB laboratory workers and radiologists, were enrolled for the study from June 2017 to June 2018. Blood samples were collected and tested using QFT-GIT and QFT-plus. The secreted IFN-γ was quantified by LFA, which took approximately 15 min, and ELISA, which took approximately 3 h. Results: A total of 176 blood samples were screened. The positive rates of QFT-GIT and QFT-plus were 34.1% and 37.5%, respectively. Overall agreement between QFT-GIT and QFT-plus was 93.1% ( κ = 0.86). The positive rates of LFA with QFT-GIT tube and QFT-plus tube were 25.6% and 31.3%, respectively, overall agreement of LFA being 90.3% ( κ = 0.78) and 89.2% ( κ = 0.77), respectively, compared to the QFT-GIT and QFT-plus ELISA. Conclusion: The ability of LFA to measure IFN-γ was similar to that of ELISA. The current findings suggested that the new LFA could be more conveniently utilized for diagnosing TB infection.
Flow cytometry analysis of CD4+IFN-γ+ T-cells for the diagnosis of mycobacterium tuberculosis infection