Identity
What is LL-37?
- Type
- Human cathelicidin antimicrobial peptide
- Amino acids
- 37
- Precursor
- hCAP18 (CAMP gene product)
- Primary activity
- Antimicrobial & immunomodulatory
- Research family
- Immune / host defense
- Use classification
- Research Use Only
Science Library · Cathelicidin antimicrobial peptide
LL-37 the science.
LL-37 is the only human cathelicidin antimicrobial peptide — a 37-amino-acid host-defense peptide released from the precursor protein hCAP18. It is one of the most studied antimicrobial peptides in biology, examined in research for its direct antimicrobial activity and its broader immune-signaling roles. The findings below come from in-vitro and animal models.
37 aa
Peptide length
hCAP18
Precursor protein
Preclinical
Evidence stage
In vitro & animal
Model systems
How it works
Mechanism at a glance
Compound
LL-37
Action
Disrupts microbial membranes
Effect
Antimicrobial & immunomodulatory signaling
Studied for
Host-defense & wound models
Evidence to date
In vitro
Animal
Human
Evidence to date: in vitro and animal models. No established human therapeutic trials for the synthetic peptide.
What it is
LL-37 (named for the two leucine residues at its N-terminus and its 37-amino-acid length) is the mature, active peptide cleaved from the human cathelicidin precursor hCAP18. It is produced by neutrophils, epithelial cells, and other tissues as part of the innate immune system — the body’s first-line, non-specific defense.
As a cationic, amphipathic peptide it interacts with negatively charged microbial membranes. Beyond direct antimicrobial action, LL-37 is studied as a signaling molecule that influences immune cells, making it a heavily used research tool in host-defense and inflammation biology.
Pathways under study
LL-37 research spans direct and indirect mechanisms:
- Membrane disruption — the classic antimicrobial mechanism, in which the cationic peptide permeabilizes microbial membranes.
- Immunomodulation — effects on chemotaxis, immune-cell recruitment, and cytokine signaling, independent of direct microbial killing.
- Wound & barrier biology — roles in re-epithelialization and tissue repair in laboratory models.
What research has explored
LL-37 literature is extensive but, for the synthetic peptide, largely in vitro and animal-model:
- Antimicrobial activity. Many studies characterize LL-37’s activity against bacteria, fungi, and viruses in culture, and how salt and protein conditions affect it.
- Immune signaling. Research examines LL-37 as a modulator of immune-cell behavior, both pro- and anti-inflammatory depending on context.
- Disease-context biology. Endogenous LL-37 has been studied across skin, lung, and inflammatory conditions, illuminating its dual host-defense and signaling roles.
These are observations on the endogenous peptide and in laboratory models; human therapeutic use of the synthetic peptide is not established.
Current state of the evidence
LL-37 is intensively characterized as an endogenous human peptide, but evidence for the synthetic peptide as an intervention is preclinical (in vitro and animal). No human therapeutic safety, dosing, or efficacy is established here. LL-37 is supplied strictly as a research material for laboratory investigation.
Compound Snapshot
At a glance
Evidence base
Research maturity
Preclinical
In vitro & animal
Endogenous human peptide
Maturity
Preclinical (synthetic peptide)
Extensive in-vitro and animal literature; no established human therapeutic trials for the synthetic peptide.
Translation
Not established in humans
Laboratory and endogenous-peptide findings do not establish human therapeutic safety, dosing, or benefit.
Sources & References
Peer-reviewed research and database records
PubChem
LL-37 / cathelicidin compound search
NIH PubChem lookup for molecular identity and structure records. View SourcePubMed
LL-37 cathelicidin antimicrobial peptide literature search
NCBI PubMed index for primary papers and reviews. View SourcePubMed
LL-37 immunomodulation & host-defense literature search
NCBI PubMed index for immunomodulatory and host-defense records. View SourceFor research use only. Not for human or veterinary use. These products have not been evaluated by the FDA. Nothing on this page is medical advice or a therapeutic claim.
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