LL-37
LL-37 is the only cathelicidin-family antimicrobial peptide produced in humans, released from neutrophils and epithelial cells, with direct membrane-disrupting antimicrobial activity plus immune-signaling roles in chemotaxis, phagocytosis, and wound repair that have been studied mainly in cell and animal models.
This page is a research-orientation summary, not a dosing guide. For anything beyond general background, read the primary literature or talk to a qualified clinician — specifics like amount, frequency, or administration aren't something we publish here.
What it does & how it works
LL-37 is the 37-residue, cathelicidin-derived peptide cleaved from hCAP18. Its amphipathic alpha-helical structure allows it to insert into and disrupt anionic bacterial membranes, giving it direct broad-spectrum antimicrobial and antibiofilm activity. Independent of this direct killing action, LL-37 also signals through host immune receptors: it acts as a chemoattractant for neutrophils, monocytes, and T cells via the formyl peptide receptor-like 1 (FPRL1/FPR2), and it enhances macrophage phagocytosis of bacteria partly through FPR2- and TLR4-linked pathways, while also increasing Fcγ receptor expression on macrophages.
Typical results seen in research
Cell-culture and animal-model studies show LL-37 has broad-spectrum antibacterial and antibiofilm activity, promotes chemotaxis of innate and adaptive immune cells, enhances bacterial phagocytosis by macrophages, and supports wound healing and angiogenesis in preclinical wound models. Evidence for these effects is predominantly preclinical (cell-based assays and animal wound/infection models); robust human clinical trial data establishing therapeutic efficacy of administered LL-37 peptide were not identified.
How it’s commonly used
LL-37 has been studied experimentally via topical/local application in animal and ex vivo wound models and via direct addition to cell cultures in immunology research. It is not an approved human therapeutic, so there is no established human clinical administration route in the peer-reviewed literature.
- Journal of Experimental Medicine · 2000 LL-37, the neutrophil granule- and epithelial cell-derived cathelicidin, utilizes formyl peptide receptor-like 1 (FPRL1) as a receptor to chemoattract human peripheral blood neutrophils, monocytes, and T cells
- Frontiers in Immunology · 2013 The Human Cathelicidin Antimicrobial Peptide LL-37 as a Potential Treatment for Polymicrobial Infected Wounds
- Journal of Leukocyte Biology · 2014 Antimicrobial peptide LL-37 promotes bacterial phagocytosis by human macrophages
Curated from published literature for research orientation. Not an exhaustive review, and not a substitute for reading primary sources.