This page summarises findings from published academic literature. It does not describe or endorse use in humans or animals.
LL-37 occupies an unusual position in the peptide literature. It is the only known human cathelicidin, which means there is no second example to compare it against. Everything known about how cathelicidins behave in humans comes from studying this one molecule.
LL-37 is a 37 amino acid cationic peptide derived from the C-terminal region of a precursor protein called hCAP-18. The name is literal: the sequence begins with two leucine residues and runs to 37 residues in total.
Two structural features define the published research. It is cationic, carrying a net positive charge, and it is amphipathic, meaning one face of the folded helix is water-attracting and the other is lipid-attracting.
That combination is what makes it interesting. A positively charged, amphipathic peptide interacts readily with negatively charged lipid membranes, and much of the literature follows from that single physical property.
The breadth here is unusual. Few single peptides carry substantial research literature across this many distinct fields.
Antimicrobial research. The largest body of work, examining interaction with bacterial membranes in vitro. The mechanistic interest is that membrane disruption is a physical mode of action rather than a receptor-mediated one, which raises different questions to most peptide research.
Immunomodulatory research. A substantial literature examines LL-37 as a signalling molecule in innate immune pathways, distinct from any direct antimicrobial activity. This is now arguably the larger research question.
Wound and tissue models. Published work examines LL-37 in cell migration and angiogenesis models.
Oncology research models. LL-37 appears in cancer cell line literature, where reported findings vary considerably by cell type. This is an area where the published results are genuinely inconsistent, and any summary that presents them as settled is misrepresenting the state of the field.
Most research peptides are studied within one field. LL-37 spans four, and there is a structural reason for that.
Because its primary characteristic is a physical interaction with membranes rather than binding at a specific receptor, its activity is not confined to cells expressing a particular target. Any system with a lipid membrane is, in principle, a system where something might be observed.
That breadth is a mixed blessing for the literature. It generates a large volume of published work across many models, and it makes attribution harder, because an observation in one cell type does not straightforwardly transfer to another. Researchers working with LL-37 tend to be explicit about model conditions for exactly that reason.
| Research area | What published literature examines |
|---|---|
| Antimicrobial | Interaction with bacterial membranes in vitro; physical rather than receptor-mediated mode |
| Immunomodulatory | Signalling in innate immune pathways, independent of direct antimicrobial activity |
| Wound and tissue models | Cell migration and angiogenesis in cell-based models |
| Oncology models | Cell line studies with markedly inconsistent published findings across cell types |
It is descriptive. The peptide sequence begins with two leucine residues, giving LL, and is 37 amino acids long.
Because its defining characteristic is a physical interaction with lipid membranes rather than binding at a specific receptor. That makes it relevant to a wide range of models, though it also makes findings harder to transfer between them.
No. LL-37 is not a licensed medicine in the United Kingdom. PerformanceLabsUK is not a pharmacy, a pharmaceutical company or a medical provider.
No. All compounds discussed on this site are supplied strictly for in vitro laboratory research use only, and are not intended for human or animal administration.
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Compounds studied in this area are listed under Immunological Research Peptides.
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