Chemokines are a family of proteins associated with the trafficking of leukocytes in immune surveillance and inflammatory cell recruitment. They are classified based on the positions of key cysteine residues. CX3CL1 is a CX3C chemokine known to induce adhesion and migration of leukocytes mediated by a membrane-bound and soluble form respectively. Recent experiments have shown that CX3CL1 can suppress the production of nitrous oxide, interleukin-6, and TNF-α in activated microglia and neuronal cells, suggesting that it may act as an intrinsic inhibitor against neurotoxicity by activated microglia. Its receptor, CX3CR1, also functions as a co-receptor for HIV-1 and HIV-2 envelope fusion and virus infection, which can be inhibited by CX3CL1.