Accuracy of QuantiFERON SARS-CoV-2 research use only assay and characterization of the CD4 + and CD8 + T cell-SARS-CoV-2 response: comparison with a homemade interferon-γ release assay.

Objectives: In this study, we aimed to characterize the SARS-CoV-2-specific T cell response detected by the QuantiFERON SARS-CoV-2 research use only assay in terms of accuracy and T cell subsets involved compared with a homemade interferon (IFN)-γ release assay (IGRA).
Methods: We evaluated T cell response by the standardized QuantiFERON SARS-CoV-2 tubes (antigen [Ag]1 and Ag2) and a homemade IGRA quantifying IFN-γ response to SARS-CoV-2 spike peptides (homemade-IGRA-SPIKE test). We evaluated the T cell subsets mediating the specific response using flow cytometry.
Results: We prospectively enrolled 66 individuals: COVID-19 or post-COVID-19 subjects and NO-COVID-19-vaccinated subjects, including healthy donors and immunocompromised subjects. The standardized kit detected 62.1% (41/66) of T cell responders. Ag2 tube showed a higher IFN-γ quantitative and qualitative response. Ag1 tube response was mainly mediated by CD4 ⁺ T cells; Ag2 tube response was mediated by CD4 ⁺ and CD8 ⁺ T cells. The homemade-IGRA-SPIKE test detected a higher number of responders (52/66, 78.8%) than the QuantiFERON SARS-CoV-2 assay (P = 0.056). The response was found in both T cell subsets, although a higher magnitude and response rate was observed in the CD4 ⁺ T cell subset.
Conclusion: The QuantiFERON SARS-CoV-2 response is mediated by CD4 ⁺ and CD8 ⁺ T cells. A lower number of responders is found compared with the homemade-IGRA-SPIKE test, likely because of the different peptide composition.
Competing Interests: Conflict of Interest CT and CG received honoraria for speaking, manuscript writing, or educational events from Merck, Biogen, Roche, Novartis Sanofi, Celgene, and Almiral. EN participates on a data safety monitoring board or advisory board and receives fees for educational training from Gilead, Eli Lilly, GS, SOBI, and Roche. EN has a patent pending for raloxifene use in COVID-19 with Dompè Pharmaceutical. DG is a member of the advisory board of Biomerieux and Eli Lilly and received fees for educational training or consultancy from Almiral, Biogen, Cellgene, Diasorin, Janssen, Qiagen, and Quidel. All the other authors declare that the research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.
(Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)