Performance comparison of a flow cytometry immunoassay for intracellular cytokine staining and the QuantiFERON (R) SARS-CoV-2 test for detection and quantification of SARS-CoV-2-Spike-reactive-IFN-gamma-producing T cells after COVID-19 vaccination
Por:
Tormo, Nuria, Gimenez, Estela, Martinez-Navarro, Maria, Albert, Eliseo, Navalpotro, David, Torres, Ignacio, Gimeno, Concepcion, Navarro, David
Publicada:
1 abr 2022
Ahead of Print:
1 feb 2022
Resumen:
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 (R)
SARS-CoV-2 Test [QF]) for detection and quantification of
SARS-CoV-2-Spike (S)-reactive-IFN-gamma-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 (R) COVID-19 vaccine (at a median of 114 days; 34-145). Prior
to vaccination, 91 were categorized as being SARS-CoV-2-naive 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-gamma-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-naive 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
SARSCoV-2 IFN-gamma- CD4(+) T-cell frequencies and IFN-gamma levels
measured in the QF Ag1 tube (P=0.78) or between the sum of SARS-CoV-2
IFN-gamma CD4(+) and CD8(+) T-cell frequencies and IFN-gamma 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.
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