CD14 and macrophage activation syndrome: A paper by Giamarellos-Bourboulis et al. [63] demonstrated that among patients with COVID-19, there was a significant downregulation of HLA-DR expression on CD14+ monocytes in both COVID-19 patients with severe immune dysregulation and with macrophage activation syndrome (MAS) when compared to both patients with intermediate severity and healthy volunteers, demonstrating a difference between the severe population and the intermediate population.