ARG1 and viral infectious disease: Markers of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs), CEACAM8 (CD66B; Figure 5G) and OLR1 (LOX-1;Figure S4C), and markers of monocytic MDSCs (M-MDSCs), IL-4R (Figure 5G), ITGAM (CD11B;Figure S4D), including a functional marker of MDSCs, ARG1 (Figure S4D), were positively correlated with the severity of viral infection.