LL-37: The Human Antimicrobial Peptide That Fights Bacteria, Fungi, Viruses, and Cancer

LL-37, the only human cathelicidin antimicrobial peptide, has demonstrated activity across three domains of infection — bacterial, fungal, and viral — through distinct mechanisms. Against bacteria, it disrupts cell membranes. Against fungi, it inhibits growth. Against viruses, it interferes with replication. Additionally, LL-37 shows immunomodulatory effects and direct cytotoxicity against cancer cells, positioning it as a potential multi-purpose therapeutic molecule.

This is a narrative review article that synthesizes published research on LL-37's antimicrobial and anti-cancer properties. The authors surveyed the literature on LL-37's mechanisms of action against bacteria, fungi, viruses, and cancer cells.

As antibiotic resistance grows, there's urgent need for alternatives. LL-37 is produced naturally by the human body, making it a well-tolerated starting point for drug development. Its ability to fight infections across multiple pathogen types while also modulating immune responses against cancer makes it unusually versatile compared to conventional antibiotics that target only bacteria.

With antibiotic-resistant infections killing over a million people annually, the search for new antimicrobial strategies has intensified. LL-37 stands out because it's already part of human innate immunity, has broad-spectrum activity, and works through membrane disruption — a mechanism that bacteria find much harder to develop resistance against. Its additional anti-cancer properties make it one of the most studied antimicrobial peptides for therapeutic development.

As a review article, this paper does not present original experimental data. Most LL-37 research has been preclinical (lab and animal studies), with limited human clinical trial data. The therapeutic potential described is largely theoretical and would require extensive clinical testing.