IL-8, also known as CXCL8, GCP-1, and NAP-1, purified from peripheral blood monocytes is a 10 kDa protein showing at least 4 variant forms (77, 72, 70, and 69 amino acids, respectively) which differ in the length of the N-terminal and readily form dimers in solution. There are many receptors on the surface membrane capable of binding IL-8; the most frequently studied types are the G protein-coupledserpentine receptors CXCR1 and CXCR2. Expression and affinity for IL-8 differs between the two receptors (CXCR1 > CXCR2). IL-8, also known as neutrophil chemotactic factor, has two primary functions. It induces chemotaxis  in target cells, primarily neutrophils but also other granulocytes, causing them to migrate toward the site of infection. IL-8 also induces phagocytosis once they have arrived. IL-8 is also known to be a potent promoter of angiogenesis.
IL-8 is often associated with inflammation. As an example, it has been cited as a proinflammatory mediator in gingivitis and psoriasis. IL-8 secretion is increased by oxidant stress, which thereby cause the recruitment of inflammatory cells and induces a further increase in oxidant stress mediators, making it a key parameter in localized inflammation. IL-8 was shown to be associated with obesity.