Defensins are small cysteine-rich cationic proteins found in both vertebrates and invertebrates. They have host defense properties, and are active against bacteria, fungi and many viruses. Beta-defensins are the most widely distributed, being secreted by leukocytes and epithelial cells of many kinds. This peptide (3.9kDa, 36-amino acids) has a beta sheet with three intramolecular disulfide bonds. It is constitutively produced by various epithelial tissues including urogenital and respiratory tracts. Its expression is also inducible in keratinocytes of whole human skin by lipopolysaccharides and peptidoglycan. hBD-1 exhibits antimicrobial activity against several pathogenic microorganisms including E.coli, although its activity is dependent on salt sensitivity, because it is inhibited by salt in a concentration-dependent manner. In addition to its antimicrobial activity, hBD-1 chemoattracts CC chemokine receptor (CCR)6-expressing HEK293 cells, implying that this peptide utilizes CCR6 as a receptor.