SARS-CoV-2-specific T-cell Detection in Whole Blood
IL-2 is a key growth factor for activated T-cells, while TNF-α and IFN-γ are considered canonical inflammatory cytokines mediating effector/memory T-cell functions. Analysis of cytokine production in stimulated T-cells confirmed that IL-2 and TNF-α were consistent markers for activated CD4+ T-cells, while activated CD8+ T-cells mainly produced TNF-α and IFN-γ. After incubating whole blood with SARS-CoV-2 Spike peptide pool, we were able to discern Spike-reactive T-cells by dual cytokine gating (Figure 1). Here, healthy individuals without history of SARS-CoV-2 infection demonstrated no significant T-cell responses to SARS-CoV-2 spike peptide. However, T-cells from SARS-CoV-2-infected or vaccinated individuals showed substantial spike-specific CD4+ and CD8+ T-cells.