In addition, and specifically in MS, the levels of IL-6 are pathologically associated with fatigue, which is characteristic of the disease, in contrast to other elements of the immune system, such as T cells and other peripheral markers of inflammation, for instance, C-reactive protein (CRP), erythrocyte sedimentation rate, or soluble forms of intercellular adhesion molecule-1 [24]. Here, CRP is linked to myeloid sarcoma.