OBJECTIVES: To identify the best experimental approach to detect a SARS-CoV-2-specific T cell response using a whole-blood platform .
METHODS: Whole-blood from 56 COVID-19 and 23``NO-COVID-19"individuals were overnight stimulated with different concentrations (0.1 or 1 µg/mL) of SARS-CoV-2 PepTivator® Peptide Pools, including spike (pool S), nucleocapsid (pool N), membrane (pool M), and a MegaPool (MP) of these three peptide pools . ELISA was used to analyse IFN-Î³ levels .
RESULTS: IFN-Î³-response to every SARS-CoV-2 peptide pool was significantly increased in COVID-19 patients compared with``NO-COVID-19"individuals . Pool S and MegaPool were the most potent immunogenic stimuli (median : 0.51, IQR : 0.14-2.17; and median : 1.18, IQR : 0.27-4.72, respectively) compared to pools N and M (median : 0.22, IQR : 0.032-1.26; and median : 0.22, IQR : 0.01-0.71, respectively). Whole-blood test based on pool S and MegaPool showed a good sensitivity of 77% and a high specificity of 96% . IFN-Î³-response was mediated by both CD4+ and CD8+ T cells, and detected independently of clinical parameters in both hospitalized and recovered patients .
CONCLUSIONS: This easy-to-use assay for detecting SARS-CoV-2-specific T cell response may be implemented in clinical laboratories as a powerful diagnostic tool.