Review: Defensins and cathelicidins in lung immunity

Innate Immun. 2010 Jun;16(3):151-9. doi: 10.1177/1753425910365734. Epub 2010 Apr 23.


Defensins were first identified in 1985 and are now recognized as part of a large family of antimicrobial peptides, divided into three categories: alpha-, beta-, and -defensins. These defensin classes differ in structure, sites of expression and biological activities. Human alpha-defensins include peptides that are expressed primarily in neutrophils, whereas human beta-defensins are widely expressed in epithelial cells, including those lining the respiratory tract. Defensins were first studied for their broad spectrum activity against bacteria, fungi and viruses; however, it is now clear that they also recruit inflammatory cells and promote innate and adaptive immune responses. Recent evidence shows that defensins have anti-inflammatory effects as well. Hence, defensins can participate in all phases of an immune response in the lung, including initial killing of pathogens and mounting - and resolution -- of an immune or inflammatory response. The cathelicidin, LL-37, is an antimicrobial peptide produced by neutrophils and respiratory epithelial cells that has similar roles in lung immunity as the defensins. A major challenge for the coming years will be to sort out the relative contributions of defensins and LL-37 to overall immune responses in the lung and to determine which of their many in vitro activities are most important for lung immunity.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Animals
  • Anti-Infective Agents / immunology
  • Cathelicidins / immunology
  • Cathelicidins / metabolism*
  • Defensins / immunology
  • Defensins / metabolism*
  • Epithelial Cells / immunology
  • Epithelial Cells / metabolism*
  • Epithelial Cells / pathology
  • Humans
  • Immunity, Innate
  • Lung / pathology
  • Neutrophils / immunology
  • Neutrophils / metabolism
  • Neutrophils / pathology


  • Anti-Infective Agents
  • Cathelicidins
  • Defensins