PDCD1LG2 and infection: Indeed, vitamin A is required for the conversion of monocyte-derived F4/80intCD206+PD-L2+MHC-II+ macrophages into cells that assume a F4/80highCD206–PD-L2–MHC-II–UCP1+ phenotype (Gundra et al., 2017), whose function during infection and/or resolution still needs to be elucidated (Figure 2).