Chemokines are a superfamily of small polypeptides that selectively control activation, adhesion, and chemotaxis of various leukocyte populations. More than 50 chemokines and 15 chemokine receptors have been described.
Different cell types express different chemokine receptors.
Some are primarily involved in inflammatory processes, while others are constitutialey expressed and play homeostatic roles.
Chemokines normally expressed in lymphoid organs or non-lymphoid tissues such as the skin direct normal trafficking.
Pro-inflammatory cytokines such as TNF or IL-1 upregulate the expression of inflammatory chemokines such as IL-8. These signals are critical for phagocytic leukocyte and lymphocyte activation, extravasation, and chemotactic migration.