In line with this finding, a study examining changes in IDO-1 activity and expression in peripheral blood mononuclear cells (PBMCs) of RRMS patients found high IDO-1 expression and serum neopterin (a marker of inflammation) with a concomitant decrease in IFN-γ in the relapse phase of MS, but not in the stable, remitting phase of disease (76). This evidence concerns the gene IFNG and myeloid sarcoma.