Earlier studies of gene expression in MS performed in whole blood and peripheral blood mononuclear cells (PBMCs) have not shown large scale differences between MS patients and healthy controls.15, –17 A study of whole blood gene expression by Parnell et al., comparing MS patients to healthy controls showed differential gene expression of EOMES and TBX21.17 Despite clear evidence for involvement of T cells illustrated by the effectiveness of treatments that target T cells, we did not detect gene expression differences for CD4+ T cells of untreated MS patients compared to healthy controls.18 Here, TBX21 is linked to myeloid sarcoma.