CCL2 and COVID-19: In this study, we showed that enriched populations of Res-like Mac (HLA-DR+ITGAM−CD68low), M1 Mac (CD68+ITGAM+CCL2+), and pro-inflammatory Mac (CD68+ITGAM−CSF1R−CCL2+) in patients with severe COVID-19 (Fig. 4a–c).