CCL17 and Alzheimer disease: Thymus and activation regulated chemokine (TARC/CCL17), a member of the Th2 chemokine family, serum level has been suggested to be a useful clinical biomarker for AD treatment and disease severity [57, 58], whereas in CTCL at disease progression chemokine receptors, expressed by skin-infiltrating T cells and surface molecules, have shown the tendency to decrease due to loss of these markers subsequently followed by diminished epidermotropism [59, 60].