LL-37

Cathelicidin LL-37 · hCAP-18 fragment

Last reviewed: 2026-05-16

CAS: 154947-66-7
MW: 4493 Da
Research focus: antimicrobial skin wound

The only human cathelicidin antimicrobial peptide — a 37-residue cationic helix studied for direct antimicrobial action, wound healing, angiogenesis, and modulation of host immune responses.

Mechanism of action

LL-37 is amphipathic and cationic, allowing it to insert into anionic microbial membranes and disrupt bilayer integrity. Beyond direct antimicrobial action, it activates formyl peptide receptor 2 (FPR2) on host cells, drives keratinocyte migration via EGFR transactivation, and stimulates angiogenesis through endothelial cell proliferation.

Research history

Identified in the 1990s as the active C-terminal cleavage product of human cationic antimicrobial protein hCAP-18. Implicated in psoriasis, rosacea, atopic dermatitis, and the innate immune response to bacterial and viral infection.

Summarised studies

LL-37 accelerates re-epithelialisation in human wounds

Heilborn J.D. et al., J Invest Dermatol · 2014

LL-37 expression at the wound edge correlated with re-epithelialisation rate in chronic ulcer biopsies; topical LL-37 application accelerated closure in animal models.

Pro-angiogenic activity of LL-37 in endothelial cells

Koczulla R. et al., J Clin Invest · 2003

LL-37 induced proliferation and tube formation in cultured human umbilical vein endothelial cells, with parallel in-vivo angiogenic effects in chick chorioallantoic membrane assays.

Safety profile

LL-37 has a dual-edged immunological profile: useful in wound repair and antimicrobial defence but implicated in autoinflammatory skin disease at elevated concentrations. Research preparations of LL-37 are highly sensitive to vehicle, ionic strength, and serum protein binding, complicating dose interpretation.

UK regulatory status

LL-37 is not a licensed medicine in the UK. Research-only laboratory use is unrestricted; clinical use is not.

Frequently asked questions

Is LL-37 the same as cathelicidin?

LL-37 is the mature, active C-terminal peptide cleaved from the cathelicidin precursor hCAP-18. 'Cathelicidin' often refers to the whole class; in humans the principal active fragment is LL-37.

How is LL-37 typically stored in research?

Lyophilised LL-37 is stored at −20 °C, preferably in a desiccated vial. Reconstituted solutions are sensitive to oxidation and adsorption to plastic; low-binding tubes and short working aliquots are recommended.

Why is LL-37 considered a 'double-edged' peptide?

While it is essential for innate immunity and tissue repair, elevated LL-37 levels are implicated in the pathogenesis of psoriasis and rosacea, demonstrating that its effects are highly context- and dose-dependent.

Where to source LL-37 for laboratory research

The following UK-based suppliers stock research-grade, lyophilised peptides for in-vitro and pre-clinical work. Purity and provenance vary; always request a Certificate of Analysis (CoA) and confirm cold-chain storage on arrival. None of the products linked below are approved for human use.

PeptideAuthority.co.uk
UK-based research peptide supplier with batch certificates of analysis and >99% purity testing.
PeptideBarn.co.uk
Wide catalogue of research-grade lyophilised peptides shipped from the UK, including bulk vials.

Appears in research stacks

Skin & Wound Healing Research Stack
Address dermal collagen synthesis, angiogenesis, and antimicrobial defence in pre-clinical wound-healing models.

Side-by-side comparisons

KPV vs LL-37
KPV and LL-37 occupy overlapping but distinct niches in the inflammation–antimicrobial peptide space. KPV is small, charge-neutral, and primarily anti-inflammatory; LL-37 is larger, cationic, and combines direct antimicrobial activity with broad immunomodulation.

Cited in research summaries

Best healing peptides for research in 2026
BPC-157 remains the most-studied research peptide for soft-tissue repair; GHK-Cu leads dermal regeneration; KPV and larazotide dominate gut-barrier research; LL-37 sits at the antimicrobial-host-defence intersection.