HLA-DRB1 and COVID-19: Notably, MCEMP1 expressing cells also expressed higher transcript expression of S100 proteins (S100A8, S100A9, S100A12) with reduced IFITM1-3 expression and HLA-DRB1 (Supplementary Fig. S6c), further reinforcing that severe COVID-19 involves an early expansion of monocytes with an immunosuppressive phenotype.