Macrophages are considered to play a seminal part in cytokine production in the joints of patients with RA, representing a major source of most of the prominent mediators of disease, such as tumor necrosis factor (TNF)-α and interleukin (IL)-6, but also other cytokines and chemokines involved in the disease process, such as IL-1β, IL-8, and chemokine (C-C motif) ligand 2 (CCL2) [4]. Here, CCL2 is linked to rheumatoid arthritis.