IL-4 can also induce DC Aldh1a2 expression/aldehyde dehydrogenase activity (17–19), and it has recently been suggested that there is interplay between RA and IL-4 in DC expression of Arg1 (20), Aldh1a2 and induction of Foxp3+ Tregs in the context of experimental autoimmune encephalomyelitis (19). This evidence concerns the gene IL4 and experimental autoimmune encephalomyelitis.