Defensin, alpha 4 (DEFA4), also known as neutrophil defensin 4 or HNP4, is a human defensin peptide that is encoded by the DEFA4 gene.[3][4] HNP4 is expressed in the granules of the neutrophil where it defends the host against bacteria[5] and viruses.[6]
Defensins are a peptide family of cytotoxic microbicides involved in innate immunity.[7] Members of the defensin family are distinguished by a conserved six-cysteine motif. Several human alpha defensin genes including HNP4 are clustered on chromosome 8. DEFA4 differs from other defensin genes by an extra 83-base segment that is apparently the result of a recent duplication within the coding region. HNP4 inhibits corticotropin-stimulated corticosterone production.[3]