CCL4 is a small cytokine that belongs to the CC chemokine subfamily. CCL4 is being secreted under mitogenic signals and antigens and hereby acts as a chemoattractant for natural killer cells, monocytes and various other immune cells in the site of inflamed or damaged tissue. CCL4 is produced by: monocytes, B cells, T cells, NK cells, dendritic cells, neutrophils, fibroblasts, endothelial cells such as vascular smooth muscle cells, brain microvessel endothelial cells, fetal microglia and epithelial cells. CCL4 is a major HIV-suppressive factor produced by CD8+ T cells.