Host-defense peptide that has antimicrobial activity against Gram-negative bacteria, and to a lesser extent also against Gram-positive bacteria and fungi (PubMed:2500436, PubMed:2501794, PubMed:15317502, PubMed:15616305, PubMed:30658057). Exhibits antimicrobial activity against Gram-negative E.coli and E.aerogenes and Gram-positive S.faecalis, S.aureus and B.cereus and the yeast C.albicans (in vitro) (PubMed:2500436, PubMed:2501794, PubMed:15317502, PubMed:15616305, PubMed:17088326, PubMed:30658057). Interacts with pathogenic surface proteins and toxins, such as HIV-1 surface protein gp120 and B.anthracis anthrax lethal factor lef (PubMed:15620707, PubMed:30658057). Protects blood cells against infection with HIV-1 (in vitro) (PubMed:15620707). Inhibits enzymatic activity of B.anthracis lef/anthrax lethal factor (in vitro) (PubMed:30658057). Inhibits corticotropin (ACTH)-stimulated corticosterone production (in vitro) (PubMed:2843187). Homodimer; homodimerization seems to be required for killing S.aureus, but not E.coli (PubMed:17088326, PubMed:30658057). Interacts with CD4 (PubMed:15620707). Interacts with HIV-1 surface protein gp120; homodimerization is required for the interaction (PubMed:15620707, PubMed:30658057). Interacts with Bacillus anthracis lef; homodimerization is required for the interaction (PubMed:30658057). Stored as mature peptide in neutrophil granules. Expressed in neutrophils (at protein level) (PubMed:2843187, PubMed:2500436, PubMed:2501794). Expressed in bone marrow (PubMed:8469233). The three-dimensional structure formed by the three intramolecular disulfide bridges is indispensable for effective bacterial killing. Belongs to the alpha-defensin family.