CCL17 and Alzheimer disease: showed that the basal mRNA expression level of thymus and activation-regulated chemokine (TARC)/C-C motif chemokine ligand 17 (CCL17) was elevated in peripheral blood mononuclear cells (PBMCs) from AD patients compared with that in PBMCs from healthy controls, while the basal mRNA expression levels of CCL8 and monocyte chemotactic protein-4 (MCP-4)/CCL13 were decreased in patients with AD (48).