THE STRUCTURE OF NEUTROPHIL DEFENSIN GENES

Defensins are a family of microbicidal peptides abundant in the granul es of mammalian neutrophils, in rabbit alveolar macrophages, and in hu man and murine intestinal Paneth cells. We cloned and sequenced the ge nes of three neutrophil-specific defensins. Human HNP-1 and HNP-3 are nearly identical and rabbit NP-3a is closely related. The four known n eutrophil-specific defensin genes are strikingly similar in the struct ure and organization of their three exons and two introns, but the thr ee defensin genes expressed in macrophages (MCP-1 and -2) or Paneth ce lls (HD-5) are organized differently: HD-5 has only two exons, and MCP -1 and -2 have a comparatively short first intron. The diverse genomic organization of defensin genes may contribute to their cell-specific expression.