Human BD-3, also known as Beta-Defensin 3, is a 67 amino acid cytokine protein encoded by the DEFB103A gene located at locus 8p23.1 on chromosome 8. After signal sequence processing and maturation, the cytokine becomes 45 amino acid residues long (from 23 to 67). Human BD-3 is known to exhibit antimicrobial activity against Gram-positive bacteria, S.aureus and S.pyogenes, Gram-negative bacteria P.aeruginosa and E.coli and the yeast C.albicans. Moreover, the cytokine kills multiresistant S.aureus and vancomycin-resistant E.faecium. This particular BD protein is expressed highly in skin and tonsils, and to a lesser extent in trachea, uterus, kidney, thymus, adenoid, pharynx and tongue. It has much lower expression in salivary glands, bone marrow, colon, stomach, polyps and larynx along with no expression in the small intestine. Furthermore, induction of BD-3 is achieved through bacterial infection or detection of lipopolysaccharides (LPS) and by IFN-γ.