Single-cell epigenomic landscape of peripheral immune cells reveals establishment of trained immunity in individuals covalescing from COVID-19

Single-cell chromatin accessibility and T cell-receptor analyses of peripheral blood mononuclear cells of individuals convalescing from COVID-19 revealed that chromatin remodeling was observed in both innate and adaptive immune cells, such as monocytes and B, NK and T cells. CD14+ or CD16+ monocytes with trained and activated epigenomic states and effecter or memory CD8+ T cells were expanded, whereas B cells were decreased in the patients convalescing from COVID-19 when they were compared with those of healthy individuals. These B cells exhibited an accelerated developmental program from immature B cells to antibody-producing plasma cells.