CD4 and COVID-19: In GSE171110, the fraction of resting dendritic cells, M2 macrophages, resting NK cells, resting memory CD4+ T cells, and CD8+ T cells were significantly higher in the healthy controls than those in the COVID-19 patients, but lower proportions of M0 macrophages, neutrophils, and plasma cells were observed in the healthy controls compared with COVID-19 patients(Figure 2B).