Defensin 5/HNP 5

Human neutrophil alpha-defensins (also designated HNPs) are small, cationic, cysteine-rich antimicrobial proteins that play important roles in innate immunity against infectious microbes such as bacteria, fungi and enveloped viruses. Alpha-defensins are synthesized as inactive precursors and are activated by proteolytic cleavage by MMP-7. Paneth cells in small intestinal crypts secrete the alpha-defensins, which are also termed cryptidins in mice. Alpha-defensins 5 and 6 probably contribute to innate defense of the GI mucosal surface by protecting against microbial invasion in states of intestinal inflammation.