Along this line, IDO activity can also dictate the patterns of disease exacerbation and remission during pregnancy in RRMS through balancing cytokine levels (Zhu et al., 2007), however more insight is needed to elucidate the levels of IDO with regards to MS relapse during pregnancy given IDO activity is evident in both relapse and successful pregnancy. Here, IDO1 is linked to myeloid sarcoma.