FOLR2 and autoimmune disease: Intriguingly, it is believed that FOLR2 (also referred to as FR-β) is commonly overexpressed in activated macrophages involved in the pathogenesis of inflammation and autoimmune diseases, such as autoimmune encephalomyelitis (Lu et al., 2014), ulcerative colitis (Poh et al., 2017b), atherosclerotic (Muller et al., 2014; Poh et al., 2017b), acute myeloid leukemia (Lynn et al., 2015), lung inflammation (Han et al., 2015), and rheumatoid arthritis (Nogueira et al., 2016; Poh et al., 2017a).