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defensin/de·fen·sin/ (de-fen´sin) any of a group of small antimicrobial cationic peptides occurring in neutrophils and macrophages.
a peptide with natural antibiotic activity found within human neutrophils. Three types of defensins have been identified, each consisting of a chain of about 30 amino acids. Similar molecules occur in white blood cells of other animal species. They show activity toward viruses and fungi, in addition to bacteria.
defensinA small (29 to 34 amino acid) cationic peptide produced in neutrophils and epithelial cells, which may be involved in nonspecific response to microbes.
ß-defensin 1—expressed in alveolar epithelia of normal individuals, but not in patients with cystic fibrosis.
ß-defensin 2—first identified in the skin of patients with psoriasis who have a decreased susceptibility to skin infections.
defensin(dē-fĕn′sĭn) [term coined by Robert I. Lehrer, U.S. physician, b. 1938]
Destructive peptides (groups of amino acids) found in the granules of neutrophils and other phagocytic cells that kill bacteria and fungi by destroying their membranes. Defensins are active against bacteria, fungi, and enveloped viruses in vitro. They may contribute to host defenses against susceptible organisms.