SPI1 and COVID-19: For example, the activity gradient of a group of TFs showed high concordance with the transcriptomic vector field of severe COVID-19 in HLA-DRlo S100Ahi monocytes, including SPI1, CEBPA, and SP1 (Fig. 5e–g and Supplementary Fig. 12), suggesting that severe COVID-19 is accompanied by increased activity of these TFs in HLA-DRlo S100Ahi monocytes.