On comparing the relative abundance of circulating CD11c+HLA-DR- proinflammatory macrophages between the COVID-19 patients with mild diseases and patients who progressed to ARDS, we found a prominent expansion of these cells in ARDS (Figures 1A, B), as reported by a number of previous studies as well (4–6). The gene discussed is ITGAX; the disease is acute respiratory distress syndrome.