Human CCL4 (C-C motif ligand 4; also known as MIP-1_) is a 69-amino-acid CC chemokine secreted by activated T cells, monocytes, and macrophages. CCL4 primarily binds CCR5 to attract monocytes, NK cells, and T lymphocytes, playing a key role in antiviral immunity and inflammation. It also binds CCR1 with lower affinity. CCL4 interacts with scavenger receptor ACKR2, which internalizes and degrades it to regulate chemokine gradients. Full-length CCL4 is processed by CD26 into CCL4(3-69), a more potent CCR5 agonist. These interactions highlight CCL4Õs role in HIV suppression, graft rejection, and chronic inflammation.
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