Defensins: natural anti-HIV peptides.

Mammalian defensins are small cationic antimicrobial peptides predominantly found in leukocytes and epithelial cells engaged in host defense. These peptides act as effector molecules in innate immunity as well as regulators in adaptive immunity. Increasing evidence indicates that defensins are effective inhibitors of HIV-1. While the level of defensins in HIV-1 infected individuals has not been determined, neutropenia and neutrophil dysfunction associated with HIV disease progression may result in altered alpha-defensin production. This review provides an overview of the structure and function of defensins, and focuses on the anti-HIV-1 activity of defensins and the mechanism of this activity. Although many questions remain, studying the complex function of defensins in innate immunity against HIV has implications for our further understanding of disease progression and for the development of novel approaches to prevention and therapy.