FIGURE 1.

Schematic showing methodology and workflow of the whole blood assay for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific adaptive immune responses. Step 1: 400 µL heparinised (NaHep) whole blood is incubated for 5 h in the presence of a SARS-CoV-2-specific peptide pool in the presence of costimulatory antibodies (i.e. CD28 and CD49d) and Brefeldin-A. Step 2: cells are incubated for 20 min in the presence of a transcription factor fixation buffer, leading to the simultaneous lysis of red blood cells and cell fixation. Step 3: cells are stained for 30 min with an optimised panel of fluorophore-labelled antibodies. Step 4: samples are acquired on a flow cytometer. Control samples are processed with a similar workflow in the absence of the SARS-CoV-2-specific peptide pool.