Preliminary evaluation of a new prototype interferon-gamma release assay for the detection of Mycobacterium tuberculosis-specific T-cell responses in patients with tuberculosis.

Screening for tuberculosis infections (TBI) using the tuberculin skin test or interferon-gamma release assays (IGRA) is crucial in controlling the global TB burden. This study evaluates the performance of a new IGRA for the detection of T-cell responses against Mycobacterium tuberculosis. Blood samples from 34 adults with tuberculosis disease (TB) and from 30 children with TB, TBI or without TB were analyzed using the prototype Quan-T-Cell TB (EUROIMMUN). The pediatric samples were additionally measured using the established QuantiFERON-TB Gold Plus assay (Qiagen). Clinical performance and inter-assay concordance were analyzed. The prototype Quan-T-Cell TB yielded positivity rates of 88.2% and 100% in adults with TB and children with TBI, respectively, at a specificity of 93.8%. Comparison between the two IGRAs showed positive, negative and overall agreement rates of 100%, 93.8% and 96.3%, respectively, with a kappa score of 0.924 indicating almost perfect agreement. Our study shows promising results of the new prototype Quan-T-Cell TB, as reflected by high concordance with the final diagnosis in adults and children and performance comparable to that of the QuantiFERON IGRA. In individual cases, the data suggest that the prototype Quan-T-Cell TB may be even more consistent with TBI-related clinical findings. Unlike the QuantiFERON assay, the Quan-T-Cell TB has a predefined borderline range, which is advantageous as it may help to differentiate non-specific variation near the cut-off, and fewer sample tubes are required per analysis. The new Quan-T-Cell TB may therefore be a good alternative to the established QuantiFERON IGRA for TBI screening. Further assay optimization is underway, including evaluation studies based on larger patient and control cohorts.
Competing Interests: Declarations. Ethical approval: The study was conducted in accordance with the guidelines of the Declaration of Helsinki and approved by the Ethics Committee of the Institute for Clinical and Experimental Medicine and Thomayer University Hospital, Prague, Czech Republic (protocol code: G-19-50, date of approval: 11 September 2019). Consent to participate: Informed consent was obtained from all subjects involved in the study. In case of children, informed consent was obtained from their parents/guardians. Competing interest: EGG, SS, DZ and VH are employees of EUROIMMUN, a company that manufactures diagnostic tests and instruments. None of these authors benefits from any potential or actual financial or non-financial gain as a result of the work. The other authors declare no conflicts of interest.
(© 2025. The Author(s).)