Posttranslational Processing of Chemokines

Under physiological and pathological conditions, low-molecular-mass chemo -tactic cytokines or chemokines provide a chemotactic gradient for the directional migration of specific leukocyte subclasses. In vivo, leukocyte migration requires a network of molecules, including cytokines, chemokines, leukocyte adhesion molecules such as selectins and integrins, and proteases (1 –3 ). This complex network provides different levels of specificity based on ligand-receptor interactions. Selectins will interact with specific glycoprotein receptors, integrins with endothelial cell adhesion molecules, and chemokines with a limited number of specific chemokine receptors. Cytokines and chemokines will alter the expression level of cellular receptors, activate adhesion molecules, and induce the release of proteases. These proteases will not only help to degrade the extracellular matrix, but more recent evidence points toward a regulatory function for proteases on cytokine and chemokine activity (1 ,4 ).