On Oct. 31, 2002, National Cancer Institute (NCI) researchers announced they had discovered that a molecule best known for its antimicrobial properties also can activate key cells in the immune response. This newly discovered function suggested the molecule, a peptide called Beta-defensin 2, may be useful in the development of more effect cancer vaccine.

Antimicrobial peptides (AMPs) are primarily known for their innate immune defense against invading microorganisms, including viruses. In addition, recent research has suggested their modulatory activity in immune induction. Given that most subunit vaccines require an adjuvant to achieve effective immune induction through the activation of innate immunity, AMPs are plausible candidate molecules for stimulating not only innate immune but also adaptive immune responses.

Human defensins are effector peptides produced by various cell types and have broad antibacterial, antiviral, and antifungal activity [20]. Defensins are small cysteine-rich cationic and amphipathic proteins. Their antiviral and antibacterial activity was originally attributed to their lipid perturbation activity because the disruption of viral glycoprotein function by membrane lipid perturbation leads to the inhibition of receptor binding and fusion of the enveloped virus to host cells. However, the observation that several classes of non-enveloped viruses are also sensitive to defensins led to the discovery of additional antiviral mechanisms of defensins.