IDO1 and myeloid sarcoma: Similarly, before-treatment, IDO expression in PBMCs was comparable in acute MS relapse to that seen in healthy controls; however, significant IDO downregulation was observed due to glucocorticoid treatment of the relapse, and IDO expression in stable MS patients in remission was found to be decreased compared to healthy controls (these alterations were more or less well reflected also by the l-kynurenine/Trp ratio values measured from the serum) [203].