Cathelicidins comprise a family of mammalian
proteins containing a C-terminal cationic antimicrobial domain that becomes active after being freed from the N-terminal
cathelin portion of the holoprotein. Many other members of this family have been identified since the first
cathelicidin sequences were reported 10 years ago. The mature
peptides generally show a wide spectrum of antimicrobial activity and, more recently, some of them have also been found to exert other
biological activities. The human
cathelicidin peptide LL-37 is chemotactic for neutrophils, monocytes, mast cells, and T cells; induces degranulation of mast cells; alters transcriptional responses in macrophages; stimulates
wound vascularization and re-epithelialization of healing skin. The porcine
PR-39 has also been involved in a variety of processes, including promotion of
wound repair, induction of angiogenesis, neutrophils chemotaxis, and inhibition of the phagocyte
NADPH oxidase activity, whereas the bovine
BMAP-28 induces apoptosis in transformed cell lines and activated lymphocytes and may thus help with clearance of unwanted cells at
inflammation sites. These multiple actions provide evidence for active participation of
cathelicidin peptides in the regulation of the antimicrobial host defenses.