Clone REA346 recognizes the human C-C motif chemokine 5 (CCL5) antigen, a 8 kDa protein also known as RANTES (regulated on activation, normal T cell expressed and secreted). CCL5 belongs to the C-C chemokine family and is a target gene of NF-κB activity. It is expressed by T lymphocytes, macrophages, platelets, synovial fibroblasts, tubular epithelium, and certain types of tumor cells. NF-κB activation by different stimuli such as CD40L or interleukin 15 (IL-15) induces CCL5 production. CCL5 plays an active role in recruiting a variety of leukocytes into inflammatory sites including T cells, macrophages, eosinophils, and basophils. In collaboration with certain cytokines that are released by T cells such as IL-2 and interferon γ (IFN-γ), CCL5 also induces the activation and proliferation of particular natural killer cells to generate C-C chemokine-activated killer cells. CCL5 produced by CD8

T cells and other immune cells has been shown to inhibit HIV entry into target cells. CCL5 activity is mediated through its binding to CCR1, CCR3, and mainly CCR5. CCR4 and CD44 are auxiliary receptors for CCL5.