Donor selection for adoptive cell therapy with CD45RA− memory T cells for COVID-19 patients, and dexamethasone and interleukin-15 effect on the phenotype, proliferation and interferon gamma release

We have previously demonstrated the safety and feasibility of adoptive cell therapy with CD45RA − memory T cells containing SARS-CoV-2-specific T cells for COVID-19 patients from an unvaccinated donor who was chosen based on human leukocyte antigen compatibility and cellular response. In this study, we examined the durability of cellular and humoral immunity within CD45RA − memory T cells and the effect of dexamethasone, the current standard of care treatment and interleukin-15, a cytokine critically involved in T-cell maintenance and survival. We performed a longitudinal analysis from previously SARS-CoV-2 infected and infection-naïve individuals covering 21 months from infection and 10 months after full vaccination with the BNT162b2 Pfizer/BioNTech vaccine. We observed that cellular responses are maintained over time. Humoral responses increased after vaccination but were gradually lost. Our results suggest that the best donors for adoptive cell therapy would be recovered individuals and two months after vaccination although further studies with larger cohorts would be needed to confirm this finding. Besides, dexamethasone did not alter cell functionality or proliferation of CD45RA − T cells at a concentration used in the clinical practice, and interleukin-15 increased the memory T-cell activation state, regulatory T cell expression, and interferon gamma release. Image, graphical abstract