Functional responsiveness of memory T cells from COVID-19 patients.

The presence of memory T cells in COVID-19 patients has been acknowledged, however the functional potency of memory responses is critical for protection. In this study, naïve, effector, effector memory, and central memory CD4+ and CD8+ T cells obtained from the COVID-19 survivors were re-exposed to autologous monocyte-derived DCs that were loaded with SARS-CoV-2 spike glycoprotein S1. Proliferation capacity, CD25, 4-1BB, and PD-1 expression, and IFN-γ, IL-6, granzyme, granulysin, and FasL secretion were enhanced in CD4+ and CD8+ effector memory and central memory T cells. Albeit being at heterogeneous levels, the memory T cells from the individuals with COVID-19 history possess functional capacities to reinvigorate anti-viral immunity against SARS-CoV-2.