Skip Navigation LinksHome > January 2007 - Volume 14 - Issue 1 > Multispecific myeloid defensins
Current Opinion in Hematology:
Myeloid biology

Multispecific myeloid defensins

Lehrer, Robert I

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Abstract

Purpose of review: This review describes recent progress in our understanding of defensins and their contributions to innate immunity. Defensins are small, cysteine-rich endogenous antibiotic peptides. Human neutrophils contain large amounts of three α-defensins (HNP-1–HNP-3), and smaller amounts of a fourth, HNP-4. Monocytes and macrophages generally lack defensins, but they release messengers that induce the synthesis of β-defensins in epithelial cells.

Recent findings: In addition to their antimicrobial and immunomodulatory effects, HNP-1–HNP-3 possess antiviral and toxin-neutralizing properties. Induction of β-defensins in epithelial cells is mediated by cell-surface Toll-like receptors or cytoplasmic peptidoglycan receptors that can recognize pathogen-associated molecules. Mutations in Nod2, a cytoplasmic peptidoglycan receptor, are associated with reduced levels of intestinal α-defensins and ileal Crohn's disease. Human defensin genes show marked copy-number polymorphism. High level constitutive expression of defensins may afford protection against HIV-1 and other defensin-sensitive pathogens. Theta-defensins (cyclic octadecapeptides found in nonhuman primates) have impressive antiviral and antitoxic properties.

Summary: The multiple properties of defensins contribute to human innate immunity against bacteria, bacterial toxins, and viruses.

© 2007 Lippincott Williams & Wilkins, Inc.

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