What Is LL-37?
LL-37 is a 37-amino-acid amphipathic, cationic peptide released from the C-terminal end of the human cathelicidin precursor protein hCAP18. Its name comes from its two leading leucine residues and its length. It is expressed by neutrophils and epithelial cells and is a central effector of innate immunity.
Being amphipathic and positively charged is fundamental to how it works: those properties let it associate with and insert into microbial membranes, which tend to carry more negative surface charge than host-cell membranes.
A Dual Mechanism: Antimicrobial And Immunomodulatory
The first arm of LL-37’s studied activity is direct antimicrobial action. It binds anionic microbial membranes and can oligomerize and form pores or otherwise disrupt membrane integrity, which is studied against a broad range of bacteria as well as some fungi and enveloped viruses.
The second arm is immunomodulation. Beyond killing microbes directly, LL-37 is studied as a host-cell modulator: it influences chemotaxis of immune cells, modulates inflammatory signaling, and participates in wound-healing and angiogenesis processes. This dual role — direct antimicrobial plus immune signaling — is why it is described as a host-defense peptide rather than simply an antibiotic-like molecule.
- LL-37 is the only human cathelicidin antimicrobial peptide, cleaved from hCAP18.
- Amphipathic and cationic: disrupts anionic microbial membranes (pore formation).
- Also immunomodulatory: chemotaxis, inflammation modulation, wound healing.
- Studied across antimicrobial, innate-immunity, and tissue-repair research.
Research Context And Handling
LL-37 appears in antimicrobial-resistance research, innate-immunity studies, and wound-healing models. Common in vitro readouts include minimum-inhibitory-concentration assays, membrane-permeabilization assays, and immune-cell migration or cytokine assays. As with any Research Use Only compound, verified identity and purity, appropriate storage, and interpretation against the primary literature are essential. It is supplied strictly for laboratory research and not for human or animal use.
Research Use Only: This guide is informational and describes research-context handling of compounds intended strictly for in vitro laboratory research. Products are not for human or animal consumption, ingestion, or injection, and are not FDA-approved. Nothing here is medical, clinical, or dosing advice.
Frequently Asked Questions
What is LL-37?
LL-37 is the only human cathelicidin-derived antimicrobial peptide, a 37-amino-acid amphipathic cationic host-defense peptide cleaved from the precursor protein hCAP18 and central to innate immunity.
How does LL-37 work?
It has a dual studied mechanism: direct antimicrobial action by disrupting anionic microbial membranes, and immunomodulation such as immune-cell chemotaxis and inflammation modulation. That dual role defines it as a host-defense peptide.
What is LL-37 studied for?
It appears in antimicrobial-resistance, innate-immunity, and wound-healing research. It is a Research Use Only compound for in vitro laboratory research, not human or animal use.