Antibacterial chemokines--actors in both innate and adaptive immunity

Several antibacterial proteins and peptides of the human innate immune system have additional roles in the regulation of adaptive immune responses. Among peptides with innate and adaptive immune functions are chemokines, a family of structurally related peptides with conserved amino-terminal motifs. Chemokines regulate leukocyte trafficking during both health and disease. In recent years, some chemokines have been shown to exert direct antibacterial activity. On the other hand, several granulebound antibacterial proteins of granulocytes, and epithelium-expressed antibacterial polypeptides, possess chemotactic activity and stimulate cells of the adaptive immune system. It is likely that during evolution, some antimicrobial peptides and proteins of innate immunity have diverged to coordinate the actions of the innate immune system and the evolutionary younger, adaptive immunity. This review aims to describe antibacterial chemokines and antibacterial peptides possessing chemotactic activity, biologic properties that link innate and adaptive immunity.