Interleukin-8 (IL-8) is a chemokine produced by macrophages and other cell types such as epithelial cells. It is also synthesized by endothelial cells, which store IL-8 in their storage vesicles, the Weibel-Palade bodies. In humans, the interleukin-8 protein is encoded by the IL8 gene. There are many receptors of the surface membrane capable to bind IL-8; the most frequently studied types are the G protein-coupled serpentine receptors CXCR1, and CXCR2. Expression and affinity to IL-8 is different in the two receptors (CXCR1 >CXCR2). Toll-like receptors are the receptors of the innate immune system. These receptors recognize antigen patterns (like LPS in gram negative bacteria). Through a chain of biochemical reactions, IL-8 is secreted and is an important mediator of the immune reaction in the innate immune system response.