Abstract
Purpose: We compared the performance of an in-house-developed flow cytometry assay for intracellular cytokine staining (FC-ICS) and a commercially-available cytokine release assay (the QuantiFERON® SARS-CoV-2 Test [QF]) for detection and quantification of SARS-CoV-2-Spike (S)-reactive-IFN-γ-producing T cells after COVID-19 vaccination.
Patients and methods: The sample included 141 individuals (all male; median age, 42 years; 20-72) who had been fully vaccinated with the Comirnaty® COVID-19 vaccine (at a median of 114 days; 34-145). Prior to vaccination, 91 were categorized as being SARS-CoV-2-naïve and 50 as SARS-CoV-2-experienced. A whole blood-based FC-ICS using 15-mer overlapping peptides encompassing the entire SARS-CoV-2 S protein was used for enumeration of virus-specific IFN-γ-producing CD4 + and CD8 + T cells. The QF test (Ag1 for CD4 + T cells and Ag2 for CD4 + and CD8 + T cells in combination) was carried out following the manufacturer’s instructions.
Results: The FC-ICS and the QF assays returned significantly discordant qualitative results in both the entire cohort (P<0.001 with QF Ag1 and QF Ag2) and in SARS-CoV-2-naïve participants alone (P=0.005 and P=0.01, respectively). Discrepant results mostly involved FC-ICS positive/QF negative specimens. Overall, no correlation was found either between SARS-CoV-2 IFN-γ- CD4 + T-cell frequencies and IFN-γ levels measured in the QF Ag1 tube (P=0.78) or between the sum of SARS-CoV-2 IFN-γ CD4 + and CD8 + T-cell frequencies and IFN-γ levels quantified in the QF Ag2 tube.
Conclusion: The data suggest a greater sensitivity for the FC-ICS assay than the QF test, and urge caution when comparing SARS-CoV-2 T-cell immune responses assessed using different analytical platforms.
Keywords: COVID-19 vaccine; Flow cytometry-based immunoassay; QuantiFERON® SARS-CoV-2; SARS-CoV-2 S protein; SARS-CoV-2 T cells.
【저자키워드】 COVID-19 vaccine, SARS-CoV-2 S protein, Flow cytometry-based immunoassay, QuantiFERON® SARS-CoV-2, SARS-CoV-2 T cells., 【초록키워드】 COVID-19, SARS-CoV-2, COVID-19 vaccine, vaccination, S protein, T cells, Test, peptide, cytokine, CD4, CD8, flow cytometry, immunoassay, sensitivity, T cell, COVID-19 vaccination, immune responses, peptides, T-cell, quantification, specimens, IFN-γ, SARS-CoV-2 S protein, T-cell immune response, Combination, Frequency, Flow, overlapping, caution, median age, individual, entire cohort, no correlation, SARS-CoV-2 S, cytokine release, QuantiFERON, intracellular cytokine staining, Enumeration, SARS-CoV-2-naïve participants, greater, was used, carried, significantly, involved, median, returned, quantified, SARS-CoV-2-naïve participant, 【제목키워드】 T cell, performance, quantification, SARS-CoV-2 test,