Human Chemokine (C-C Motif) Ligand 3 (CCL3) is a small cytokine belonging to the CC chemokine family. CCL3 is primarily expressed in T cells, B cells, and monocytes after antigen or mitogen stimulation. CCL3 exhibits chemoattractive and adhesive effects on lymphocytes. CCL3 exerts multiple effects on hematopoietic precursor cells and inhibits the proliferation of hematopoietic stem cells in vitro as well as in vivo. CCR1 and CCR5 have been identified as functional receptors for CCL3.